Question

The area of ABC is 12 square units. Find
the area of ABD

Answer 1

Orient the triangle so that BC is the base. Let's stay that the length of BC is b. The triangle has some height, h, from the base to point A.

Then the area of the triangle A = 1/2 * b * h = 12

Now, if we cut BC in half, the base of triangle ABD, which we'll call b', is b' = 1/2 * b, and h has stayed the same.

So the area of ABD, which I'll call A' is

A' = 1/2 * b' * h = 1/2 * 1/2 * b * h = 1/2 * A = 1/2 * 12 = 6