For this question we need to use the Pythagorean Theorem (a2+b2=c2) since the rectangle is being divided into two triangles.
we know the length of the triangle (63) and we know the hypotenuse (65) but not the width. To find the width, we can plug the values we know into our formula.
(63) squared + b squared = (65) squared
solve.
3969 + b squared = 4225
subtract 3969 from both sides.
b squared = 256
√b² = √256
b=16