Answer:
Part 7) 
Part 8) 
Step-by-step explanation:
Part 7) Find the length of AB
we know that
The<u><em> two tangent theorem</em></u> states that if we draw two lines from the same point which lies outside a circle, such that both lines are tangent to the circle, then their lengths are the same
so
In this problem, applying the two tangent theorem
AB=BC
substitute the given values

solve for x

Find the length of AB

substitute the value of x

Part 8) we know that
If CD is tangent to circle E at point C
then
Line segment CD is perpendicular to line segment EC (radius) and CDE is a right triangle
so
Applying the Pythagorean Theorem in the right triangle CDE

substitute the given values

solve for x
