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Bunuel

What is the area of the triangle shown above?


A. \(\frac{25\sqrt{2}}{3}\)

B. \(\frac{25\sqrt{3}}{2}\)

C. 25

D. \(25\sqrt{2}\)

E. \(25\sqrt{3}\)

Attachment:
image007.jpg

Since angles in a triangle must add to 180°, we can see that the missing angle is 60°, which means we have a Special 30-60-90 Special Triangle
So let's compare the given 30-60-90 triangle with the base 30-60-90 triangle


In the base triangle, the side opposite the 90-degree angle has length 2, and in the given triangle, the side opposite the 90-degree angle has length 10
10/2 = 5, which means the given triangle is 5 times the size of the base triangle

Now that we know the Magnification Factor, we can determine the lengths of the remaining sides.

In the base 30-60-90 triangle, the side opposite the 30-degree angle has length 1
So, in the given triangle, x = (5)(1) = 5

Likewise, in the base 30-60-90 triangle, the side opposite the 60-degree angle has length √3
So, in the given triangle, x = (5)(√3) = 5√3
We get:


We now have enough information to find the area of a triangle.

Area of triangle = (base)(height)/2
If we let side AC be the base, and let side CB be the height, then the area = (5)(5√3)/2 = (25√3)/2

Answer: B

Cheers,
Brent

Hi BrentGMATPrepNow, not quite sure what's the reason of using AC be the base and CB be the height? When I use AB be the base and AC be the heigh but not getting the same answer 10 * 5/2 = 25 ? Thanks Brent
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BrentGMATPrepNow



We now have enough information to find the area of a triangle.

Area of triangle = (base)(height)/2
If we let side AC be the base, and let side CB be the height, then the area = (5)(5√3)/2 = (25√3)/2

Answer: B

Cheers,
Brent

Hi BrentGMATPrepNow, not quite sure what's the reason of using AC be the base and CB be the height? When I use AB be the base and AC be the heigh but not getting the same answer 10 * 5/2 = 25 ? Thanks Brent

The height of a triangle is always perpendicular to whatever base you have decided to use.
If you're using side AB as the base, then you must figure out what the height is, because side AC will not be at the base since AC is not perpendicular to side AB.
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Kimberly77
BrentGMATPrepNow



We now have enough information to find the area of a triangle.

Area of triangle = (base)(height)/2
If we let side AC be the base, and let side CB be the height, then the area = (5)(5√3)/2 = (25√3)/2

Answer: B

Cheers,
Brent

Hi BrentGMATPrepNow, not quite sure what's the reason of using AC be the base and CB be the height? When I use AB be the base and AC be the heigh but not getting the same answer 10 * 5/2 = 25 ? Thanks Brent

The height of a triangle is always perpendicular to whatever base you have decided to use.
If you're using side AB as the base, then you must figure out what the height is, because side AC will not be at the base since AC is not perpendicular to side AB.

Got it thanks BrentGMATPrepNow. Base can be any side but height must be perpendicular to the chosen base.
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