The measure of central angle RST is pi radians. What is the area of the shaded sector?

The area of the shaded region is  

Step-by-step explanation:

we know that

The area of complete circle subtends a central angle of 2π radians

so

A central angle of π radians subtends an area of semicircle

The area of semicircle is given by the formula

we have

substitute

therefore

The area of the shaded region is  

the first one, all those points on the line just make a strait line.

b

step-by-step explanation: