Need with two questions i am not good with this

Part 12)

Part 13)

Step-by-step explanation:

Part 12) we know that

The equation of a circle in center-radius form is equal to

where

(h,k) is the center of the circle

r is the radius of the circle

In this problem

Looking at the graph

The center is the

The radius is

substitute in the expression above

Part 13) we know that

The measure of the external angle is the semi-difference of the arcs it covers.

so

we have

$18 was the price of the t-shirt

step-by-step explanation:

168

step-by-step explanation:

i am pretty sure that the answer is 168