Author 
Message 
TAGS:

Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 49271

In the figure given below, the length of PQ is 12 and the length of PR
[#permalink]
Show Tags
16 Apr 2015, 05:11
Question Stats:
71% (02:36) correct 29% (03:09) wrong based on 123 sessions
HideShow timer Statistics



Intern
Joined: 20 Mar 2015
Posts: 6

Re: In the figure given below, the length of PQ is 12 and the length of PR
[#permalink]
Show Tags
16 Apr 2015, 06:07
Bunuel wrote: Attachment: Ques3.jpg In the figure given below, the length of PQ is 12 and the length of PR is 15. The area of right triangle STU is equal to the area of the shaded region. If the ratio of the length of ST to the length of TU is equal to the ratio of the length of PQ to the length of QR, what is the length of TU? (A) (9√2)/4 (B) 9/2 (C) (9√2)/2 (D) 6√2 (E) 12 Kudos for a correct solution.Hello, By pythagoras theorem, Side QR = 9 Now area of Triangle PQR = 1/2 * 12 * 9 = 54. We also know that, Area of Triangle PQR  Area of shaded region = Area of Triangle STU. Therefore Area of Triangle PQR = Area of Triangle STU + Area of Shaded Region So, Area of Triangle PQR = 2 (Area of Triangle STU) (Since Area of Triangle STU = Area of shaded region) So Area of Triangle STU = 54/2 = 27. Side PQ : QR = Side ST : TU 12 : 9 = 4x : 3X Now A(triangle STU) = 1/2 * 4x * 3x = 27 Solving X = 3/√2 Side TU = 3 * 3/√2= 9/√2 = 9√2/2 So the ans is C



Retired Moderator
Status: On a mountain of skulls, in the castle of pain, I sit on a throne of blood.
Joined: 30 Jul 2013
Posts: 344

Re: In the figure given below, the length of PQ is 12 and the length of PR
[#permalink]
Show Tags
16 Apr 2015, 09:56
Bunuel wrote: In the figure given below, the length of PQ is 12 and the length of PR is 15. The area of right triangle STU is equal to the area of the shaded region. If the ratio of the length of ST to the length of TU is equal to the ratio of the length of PQ to the length of QR, what is the length of TU? (A) (9√2)/4 (B) 9/2 (C) (9√2)/2 (D) 6√2 (E) 12 Kudos for a correct solution.144+QR^2=225 QR^2=81 QR=9 Area of Triangle PQR=1/2*12*9=54 Half of 54 is the area of STU ST*TU=54...(1) \(\frac{ST}{TU}\)=\(\frac{12}{9}\) \(\frac{ST}{TU}\)=\(\frac{4}{3}\) ST=\(\frac{4TU}{3}\)...(2) Replacing (2) in (1) \(\frac{4}{3}\) \(TU^2\)=54 \(TU^2\)=\(\frac{81}{2}\) TU=\(\frac{9}{\sqrt{2}}\) Answer: C



Senior Manager
Joined: 27 Dec 2013
Posts: 262

Re: In the figure given below, the length of PQ is 12 and the length of PR
[#permalink]
Show Tags
16 Apr 2015, 10:03
yes, Plus one for C. Straight forwrad question. Bunuel wrote: In the figure given below, the length of PQ is 12 and the length of PR is 15. The area of right triangle STU is equal to the area of the shaded region. If the ratio of the length of ST to the length of TU is equal to the ratio of the length of PQ to the length of QR, what is the length of TU? (A) (9√2)/4 (B) 9/2 (C) (9√2)/2 (D) 6√2 (E) 12 Kudos for a correct solution.
_________________
Kudos to you, for helping me with some KUDOS.



Current Student
Joined: 25 Nov 2014
Posts: 99
Concentration: Entrepreneurship, Technology
GPA: 4

Re: In the figure given below, the length of PQ is 12 and the length of PR
[#permalink]
Show Tags
16 Apr 2015, 10:15
C for me too.. PQR : 345 rt triangle. Thus QR = 9. Given , ST/TU = PQ/QR = 12/9 = 4/3 => ST = 4*TU/3 Now, area PQR = 2*area(STU) => 12*9/2 = ST*TU = 4*TU^2/3 => TU^2 = 81/2 => TU = 9/sqrt(2) Thus ans C.
_________________
Kudos!!



Manager
Joined: 15 May 2014
Posts: 62

Re: In the figure given below, the length of PQ is 12 and the length of PR
[#permalink]
Show Tags
18 Apr 2015, 22:00
Given PQ = 12, PR = 15, area of right triangle STU is equal to the area of the shaded region then Area of \(\triangle STU\,=\,\frac{1}{2}\) Area of \(\triangle PQR\)
\(\triangle PQR\) is a right triangle \(QR^2\,=\,PR^2\,\,PQ^2\) \(QR^2\,=\,15^2\,\,12^2\) \(QR\,=\,9\) Area of \(\triangle PQR\,=\,\frac{1}{2}*12*9\)\(\,=\,54\) So Area of \(\triangle STU\,=\,27\)
Given \(\frac{ST}{TU}\,=\,\frac{PQ}{QR}\);\(\triangle PQR\,\)and\(\,\triangle STU\) are similar \((Ratio\,of\,Sides)^2\,=\,(Ratio\,of\,Areas)\) \(\frac{TU^2}{QR^2}\,=\,\frac{Area\,of\,\triangle STU}{Area\,of\,\triangle PQR}\) \(TU^2\,=\,\frac{81*27}{54}\) \(TU^2\,=\,\frac{81}{2}\) \(TU\,=\,\frac{9}{\sqrt{2}}\,=\,\frac{9\sqrt{2}}{2}\)
Answer C



Director
Joined: 21 May 2013
Posts: 649

Re: In the figure given below, the length of PQ is 12 and the length of PR
[#permalink]
Show Tags
19 Apr 2015, 03:32
Bunuel wrote: In the figure given below, the length of PQ is 12 and the length of PR is 15. The area of right triangle STU is equal to the area of the shaded region. If the ratio of the length of ST to the length of TU is equal to the ratio of the length of PQ to the length of QR, what is the length of TU? (A) (9√2)/4 (B) 9/2 (C) (9√2)/2 (D) 6√2 (E) 12 Kudos for a correct solution.QR=\sqrt{225144}=9 Area of triangle PQR=1/2*9*12=54 Therefore, Area of each of the two triangles=27 And, 1/2*ST*TU=27 ST*TU=54 But ST/TU=PQ/QR=12/9=4:3 Therefore,4TU*TU/3=54 TU=9\sqrt{2}/2 Answer C



Math Expert
Joined: 02 Sep 2009
Posts: 49271

Re: In the figure given below, the length of PQ is 12 and the length of PR
[#permalink]
Show Tags
20 Apr 2015, 05:20
Bunuel wrote: In the figure given below, the length of PQ is 12 and the length of PR is 15. The area of right triangle STU is equal to the area of the shaded region. If the ratio of the length of ST to the length of TU is equal to the ratio of the length of PQ to the length of QR, what is the length of TU? (A) (9√2)/4 (B) 9/2 (C) (9√2)/2 (D) 6√2 (E) 12 Kudos for a correct solution. VERITAS PREP OFFICIAL SOLUTIONThe information given in the question seems to overwhelm us but let’s take it a bit at a time. “length of PQ is 12 and the length of PR is 15” PQR is a right triangle such that PQ = 12 and PR = 15. So PQ:PR = 4:5. Recall the 345 triplet. A multiple triplet of 345 is 91215. This means QR = 9. “ratio of the length of ST to the length of TU is equal to the ratio of the length of PQ to the length of QR” ST/TU = PQ/QR The ratio of two sides of PQR is equal to the ratio of two sides of STU and the included angle between the sides is same ( = 90). Using SAS, triangles PQR and STU are similar. “The area of right triangle STU is equal to the area of the shaded region” Area of triangle PQR = Area of triangle STU + Area of Shaded Region Since area of triangle STU = area of shaded region, (area of triangle PQR) = 2*(area of triangle STU) In similar triangles, if the sides are in the ratio k, the areas of the triangles are in the ratio k^2. If the ratio of the areas is given as 2 (i.e. k^2 is 2), the sides must be in the ratio √2 (i.e. k must be √2). Since QR = 9, TU must be 9/√2. But there is no 9/√2 in the options – in the options the denominators are rationalized. TU = 9/√2 = (9*√2)/(√2*√2) = (9*√2)/2. Answer (C) The question could take a long time if we do not remember the Pythagorean triplets and the area of similar triangles property. Takeaways:Pythagorean triplets you should know: (3, 4, 5), (5, 12, 13) and (8, 15, 17) and their multiples. In similar triangles, if the sides are in the ratio k, the areas of the triangles are in the ratio k^2.
_________________
New to the Math Forum? Please read this: Ultimate GMAT Quantitative Megathread  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



Current Student
Joined: 12 Aug 2015
Posts: 2651

Re: In the figure given below, the length of PQ is 12 and the length of PR
[#permalink]
Show Tags
28 Apr 2017, 19:49
Excellent Question.
Here is what i did on this one >
In Triangle PQR => Using pythagorus => PQ=12,PR=15 and =>QR=9 Area PQR=1/2 *12*9 => 54 Shaded area => 54 Area(STU)
As per question = 54Area(STU)=Area(STU) 2*Area(STU)=> 54 Area(STU)=27
For the ease of writing=>Let TU=x ST=y
Area (STU)=> xy/2 = 27 Hence xy=54
Now x/y=12/9 Multiplying the two above equations => y^2=72 => y=6√2
Hence x=> 54/(6√2) => (9√2)/2
SMASH THAT C.
_________________
MBA Financing: INDIAN PUBLIC BANKS vs PRODIGY FINANCE! Getting into HOLLYWOOD with an MBA! The MOST AFFORDABLE MBA programs!STONECOLD's BRUTAL Mock Tests for GMATQuant(700+)AVERAGE GRE Scores At The Top Business Schools!




Re: In the figure given below, the length of PQ is 12 and the length of PR &nbs
[#permalink]
28 Apr 2017, 19:49






