Astone is dropped into some water and a circle of radius r is formed and slowly expands. the perimeter of the circle is increasing at 3 m/ s. at the moment the radius is exactly 2m, what rate is the radius of the circle increasing?

answer: option a.

step-by-step explanation:

you know that the quadrilateral opqr ( a four sided figure) is inscribed in circle. this means that all its vertices are on the circle.

then, by definition, the opposite angles of the quadrilateral are supplementary, this means that the sum of their measures is 180 degrees.

you can observe in the figure that the angles ∠opq   and the angle ∠orq   are opposite, therefore:

then, can be used to d to calculate the measure of ∠opq