Prove the formula A= (1/2)r^2(theta) for the area of a sector ofa circle with radius r and central angle theta. (hint: assume 0

Prove the formula A= (1/2)r^2(theta) for the area of a sector of a circle with radius r and central angle theta.

(hint: assume 0<>< pi/2="" and="" place="" the="" center="" of="" the="" circle="" at="" the="" origin="" so="" it="" has="" the="" equation="" x^2="" +="" y^2="r^2." then="" a="" is="" the="" sum="" of="" the="" area="" of="" the="" triangle="" poq="" and="" the="" area="" of="" the="" region="" pqr="" in="" the="" figure.="">

If someone could write out the work that would be apperciated. I did it, but im not sure its correct.