Super easy 4th grade level problem

Ntriangle abc, m∠a = 35° and m∠b = 40°, and a=9. which equation should you solve to find b?

A3cm×3cm\greend{3\,\text{cm} \times 3\,\text{cm}} 3cm×3cm start color greend, 3, space, c, m, times, 3, space, c, m, end color greend rectangle sits inside a circle with radius of 4cm\blued{4\,\text{cm}} 4cm start color blued, 4, space, c, m, end color blued . what is the area of the shaded region? round your final answer to the nearest hundredth.

Using the rise/run counting method, the slope of the line is