### Home > GC > Chapter 12 > Lesson 12.1.2 > Problem12-18

12-18.

The secant-tangent angle is half the difference between the major and minor arcs.

The total measure of all the arcs in a circle is 360°.

$x=\frac{153^{\circ}-87^{\circ}}{2}=33^{\circ}$

The area of a circle is πr2.

Refer to Lesson 11.2.3 for help with the relationships.