Find the measure of b.

A. 70
B. 110
C. 75
D. 100

C. 75

Concept:

Here, we need to know the idea of quadrilaterals in a circle.

The opposite angles of quadrilaterals in a circle (cyclic quadrilaterals) are supplementary, meaning they add up to 180°

If you are still confused, please refer to the attachment below for a graphical explanation.

Solve:

Given information

The opposite angle of b = 105°

Given expression

b + opposite angle of b = 180°

Substitute values into the expression

b + 105 = 180

Subtract 105 on both sides

b + 105 - 105 = 180 - 105

b = 75°

Hope this helps!! :)

Please let me know if you have any questions