Author 
Message 
TAGS:

Hide Tags

Intern
Joined: 14 May 2010
Posts: 5

Re: Math: Triangles [#permalink]
Show Tags
17 Jun 2010, 12:06
Quote: Usually called "half of base times height", the area of a triangle is given by the formula below. • A=\frac{hb}{2}
Other formula: • A=\frac{P*r}{2}
• A=\frac{abc}{4R}
Where b is the length of the base, a and c the other sides; h is the length of the corresponding altitude; R is the Radius of circumscribed circle; r is the radius of inscribed circle; P is the perimeter Just to clarify, is P the perimeter of the circle or the triangle? Quote: • For an isosceles triangle with given length of equal sides right triangle (included angle) has the largest area. Will u elaborate on this please? I'm not sure how this works. Thanks a lot of the summary, very complete and succinct! :D



Math Expert
Joined: 02 Sep 2009
Posts: 39702

Re: Math: Triangles [#permalink]
Show Tags
18 Jun 2010, 02:14
bely202 wrote: Quote: Usually called "half of base times height", the area of a triangle is given by the formula below. • A=\frac{hb}{2}
Other formula: • A=\frac{P*r}{2}
• A=\frac{abc}{4R}
Where b is the length of the base, a and c the other sides; h is the length of the corresponding altitude; R is the Radius of circumscribed circle; r is the radius of inscribed circle; P is the perimeter Just to clarify, is P the perimeter of the circle or the triangle? Quote: • For an isosceles triangle with given length of equal sides right triangle (included angle) has the largest area. Will u elaborate on this please? I'm not sure how this works. Thanks a lot of the summary, very complete and succinct! :D 1. P is the perimeter of the triangle. 2. For instance if we have an isosceles triangle with equal sides of 1, the area will be greatest when it is a right angled triangle (max area in this case would be 1/2).
_________________
New to the Math Forum? Please read this: All You Need for Quant  PLEASE READ AND FOLLOW: 12 Rules for Posting!!! Resources: GMAT Math Book  Triangles  Polygons  Coordinate Geometry  Factorials  Circles  Number Theory  Remainders; 8. Overlapping Sets  PDF of Math Book; 10. Remainders  GMAT Prep Software Analysis  SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS)  Tricky questions from previous years.
Collection of Questions: PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.
What are GMAT Club Tests? Extrahard Quant Tests with Brilliant Analytics



Intern
Joined: 14 May 2010
Posts: 5

Re: Math: Triangles [#permalink]
Show Tags
21 Jun 2010, 10:25
Thank you for the explanation



Manager
Joined: 23 Oct 2009
Posts: 84
Location: New Delhi, India
Schools: Chicago Booth, Harvard, LBS, INSEAD, Columbia

Re: Math: Triangles [#permalink]
Show Tags
06 Jul 2010, 06:00
Under Insoceles triangle section: To find the base given the leg and altitude, use the formula:... How do you derive these formulae? What's the logic behind them???
_________________
Read about my GMAT prep at http://gmatting.blogspot.com/ 1st Feb '11  Actual GMAT : 730 (Q48 V42) AWA 6.0
My Practice GMAT Scores 29th Jan '11  GMATPrep#2 : 700 (Q47 V38) 23rd Jan '11  MGMAT Practice Test #3 : 670 (Q45 V36) 19th Jan '11  GMATPrep#1 v.1 : 710 (Q49 V37) 15th Jan '11  GMATPrep#1 : 720 (Q47 V42) 11th Jan '11  MGMAT Practice Test #2 : 740 (Q47 V44) 6th Jan '11  Kaplan#2 : 620 (Q40 V35) 28th Dec '10  PowerPrep#1 : 670 (Q47 V35) 30th Oct '10  MGMAT Practice Test #1 : 660 (Q45 V35) 12th Sept '10  Kaplan Free Test : 610 (Q39 V37) 6th Dec '09  PR CAT #1 : 650 (Q44 V37) 25th Oct '09  GMATPrep#1 : 620 (Q44 V34)
If you feel like you're under control, you're just not going fast enough. A goal without a plan is just a wish. You can go higher, you can go deeper, there are no boundaries above or beneath you.



Manager
Joined: 15 Mar 2010
Posts: 99

Re: Math: Triangles [#permalink]
Show Tags
07 Jul 2010, 20:49
simply waoww.. wish i could have given you more than one +1...kudos
_________________
If you like my post, consider giving me a kudos. THANKS!



Manager
Joined: 04 Feb 2010
Posts: 195

Re: Math: Triangles [#permalink]
Show Tags
07 Jul 2010, 23:33
Wow, thanks for this summary!



Intern
Joined: 11 Jul 2010
Posts: 2

Re: Math: Triangles [#permalink]
Show Tags
22 Jul 2010, 03:25
Under Equilateral triangles its been mentioned that "For any point P within an equilateral triangle, the sum of the perpendiculars to the three sides is equal to the altitude of the triangle.' Could you please help me out with this? I am not able to comprehend. Also are the perpendicular bisectors and the altitudes the same in case of an equilateral triangles. Thanks Bunuel!!! I am hunting and tracking down every post that your have posted in this forum. All of them that I have read till now have been extremely clear, precise and are tuned to the GMAT. Thanks again!



Math Expert
Joined: 02 Sep 2009
Posts: 39702

Re: Math: Triangles [#permalink]
Show Tags
22 Jul 2010, 04:06
sanram2205 wrote: Under Equilateral triangles its been mentioned that "For any point P within an equilateral triangle, the sum of the perpendiculars to the three sides is equal to the altitude of the triangle.' Could you please help me out with this? I am not able to comprehend. Also are the perpendicular bisectors and the altitudes the same in case of an equilateral triangles. Thanks Bunuel!!! I am hunting and tracking down every post that your have posted in this forum. All of them that I have read till now have been extremely clear, precise and are tuned to the GMAT. Thanks again! You won't need first one for GMAT. As for the second question: in equilateral triangle angle bisectors, medians and altitudes (heights) are the same and equal in length.
_________________
New to the Math Forum? Please read this: All You Need for Quant  PLEASE READ AND FOLLOW: 12 Rules for Posting!!! Resources: GMAT Math Book  Triangles  Polygons  Coordinate Geometry  Factorials  Circles  Number Theory  Remainders; 8. Overlapping Sets  PDF of Math Book; 10. Remainders  GMAT Prep Software Analysis  SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS)  Tricky questions from previous years.
Collection of Questions: PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.
What are GMAT Club Tests? Extrahard Quant Tests with Brilliant Analytics



Intern
Joined: 28 May 2010
Posts: 33

Re: Math: Triangles [#permalink]
Show Tags
24 Jul 2010, 07:01
Quote: m=\sqrt{\frac{2b^2+2c^2a^2}{4}}, where a, b and c are the sides of the triangle and a is the side of the triangle whose midpoint is the extreme point of median m. What does extreme point of median m mean?



Math Expert
Joined: 02 Sep 2009
Posts: 39702

Re: Math: Triangles [#permalink]
Show Tags
24 Jul 2010, 08:30



Manager
Joined: 16 Feb 2010
Posts: 225

Re: Math: Triangles [#permalink]
Show Tags
30 Aug 2010, 14:22
amazing! one day GMATclub might get to publish its own book : )



Intern
Joined: 03 Aug 2010
Posts: 22

Re: Math: Triangles [#permalink]
Show Tags
31 Aug 2010, 23:03
This is awesome...thanks!!!!
_________________
Welcome to my paintings website  Wholesale Art Mall.



Intern
Joined: 01 Oct 2010
Posts: 4

Re: Math: Triangles [#permalink]
Show Tags
10 Oct 2010, 23:14
gmatdelhi wrote: Under Insoceles triangle section: To find the base given the leg and altitude, use the formula:...
How do you derive these formulae? What's the logic behind them??? The explanation is based on simple fact that  In an Isosceles triangle the Altitude (coming from the vertex holding equal sides to the base) is Same as its Median. ie., Altitude ( which forms 90 degrees with base cuts the base in 2 equal parts).. Therefore Applying Phythogras theorem for L is hypotenuse A is side B/2 is another side Therefore L square = A Square + (B/2) Square All the 3 formulas shown in the page are same , and derived from this only. Hope this clarifies. Regards, Sridhar.



Intern
Joined: 10 Aug 2007
Posts: 4

Re: Math: Triangles [#permalink]
Show Tags
16 Oct 2010, 09:48
Another useful property for triangles,
If the sum of any two angles of a triangle equals the third angle then the triangle must be a right triangle i.e. If the angles of a triangle are A, B and C, Then
=> A + B = C
But for any triangle A + B + C = 180
=> 2C = 180 or C = 90



Manager
Joined: 01 Nov 2010
Posts: 177
Location: Zürich, Switzerland

Re: Math: Triangles [#permalink]
Show Tags
10 Nov 2010, 14:36
Quote: In similar triangles, the sides of the triangles are in some proportion to one another. Hey Bunuel, a very small correction. Above statement should be  In similar triangles, the sides of the triangles are in same proportion to one another.



Intern
Joined: 01 Jan 2011
Posts: 1

Re: Math: Triangles [#permalink]
Show Tags
06 Jan 2011, 11:55
Wow thank you so much!! This will be the great GMAT math book since sliced bread
Medians woah!!!! What I would do in a GMAt exam if I knew all these facts, I would beat the GMAT!
Writing in two day sand this is my final brush up of all my concepts ... great job ...



Manager
Joined: 02 Oct 2010
Posts: 149

Re: Math: Triangles [#permalink]
Show Tags
11 Jan 2011, 12:18
Excellent post. I went through all this triangle formulas and it is very very helpful......



Intern
Joined: 11 May 2008
Posts: 8

Re: Math: Triangles [#permalink]
Show Tags
04 Feb 2011, 14:13
A very useful collection !! Thank you!  +



Manager
Joined: 18 Aug 2010
Posts: 90

Re: Math: Triangles [#permalink]
Show Tags
05 Feb 2011, 14:29
Material is Great !!! + KUDO FROM ME



Senior Manager
Joined: 19 Oct 2010
Posts: 261
Location: India
GPA: 3

Re: Math: Triangles [#permalink]
Show Tags
22 Apr 2011, 07:11
Hi Bunuel, Can you please explain the last point in the median section?
_________________
petrifiedbutstanding




Re: Math: Triangles
[#permalink]
22 Apr 2011, 07:11



Go to page
Previous
1 2 3 4 5
Next
[ 95 posts ]




