# Math Help - Area & Volume

1. ## Area & Volume

Calculate the following (pls see attachment)
1. length of AB in millimetres
2. area of the semicircle in sq millimetres

2. Originally Posted by Risrocks
Calculate the following (pls see attachment)
1. length of AB in millimetres
2. area of the semicircle in sq millimetres
As for the question, part 1 can be answered by applying the Pythagorean Theorem to the triangle. You will only end up with one unknown, since $\overline{AB} = \overline{AD}$.
For part 2, use the formula for the area of a circle. A circle of radius $r$ has an area of $\pi r^2$, so a semicircle will have half that area: $\frac12\pi r^2$.