Data Sufficiency

LUANDATO wrote:

Given BD perpendicular to AC, what is the area of triangle BCD?

1) Angle BAD=69°
2) BD=CD

The OA is B.

I'm really confused with this DS question. Please, can any expert assist me with it? Thanks in advanced.

The area of rightangled triangle BCD = 1/2*BD*CD

1) Angle BAD = 69°

No information about BD and CD. Insufficient.

2) BD = CD

Since the traingle ABD is a rightangled traingle, we have BD^2 = AB^2 - AD^2 => BD^2 = 11^2 - 4^2 = 121 - 16 = 105.

We know that the area of rightangled triangle BCD = 1/2*BD*CD = 1/2*BD^2; since BD = CD

The area of the rightangled traingle BCD = 1/2*BD^2 = 1/2*105 = 105/2. Sufficient.

The correct answer: B

Hope this helps!

-Jay
_________________
Manhattan Review GMAT Prep

Locations: Stamford | Istanbul | Evanston | Seoul | and many more...

Schedule your free consultation with an experienced GMAT Prep Advisor! Click here.