A) Pine Road and Oak Street form a right angle, so we can extract the relation

where

is the distance we want to find (bottom side of the rectangle).
Alternatively, we can use the other given angle by solving for

in

but we'll find the same solution either way.
b) Pine Road and Oak Street form a right triangle, with Main Street as its hypotenuse. We can use the Pythagorean theorem to find how long it is.

Let

be the length of Main Street. Then

but of course the distance has to be positive, so

.