how do i look in these pic and what's 64.3times 4.0281 please do not delete i need this answer delete after a day please ill friend you

Alex drew a circle with right triangle prq inscribed in it, as shown below: the figure shows a circle with points p, q, and r on it forming an inscribed triangle. side pq is a chord through the center and angle r is a right angle. arc qr measures 80 degrees.

How do you find the circumfrance of a circle?

Precalculus question, image attached.