2015
Problem - 2563
In $\bigtriangleup ABC$, $AB=BC=29$, and $AC=42$. What is the area of $\bigtriangleup ABC$?
Answer
420
The answer is $\boxed{420}$.
Draw the altitude $BD\perp AC$, then $AD=CD=21$. By Pythagorean theory, we find $$AD =\sqrt{29^2 - 21^2}=20$$
Hence the area of $\triangle{ABC}=20\times 42/2 = 420$.