Question 7 1 pts To calculate the surface area of a sphere of radius R, we can use the formula b S= / 2xf(a) /1+ [f'(x)]" da . Which function should we use as f() ? Oy = VR' - x2 Oy = R Oy=x2 + R2 Oy=va' - R2 O + R2Question 8 1 pts Use Example 3 (from page 463) as a guide, and choose the correct answer. [cos(2a) sin(3x) + sin(2x ) cos (3x )] dr = O 1 -cos (5x) + C O 1 - sin(5x) + C 0 1 5 - cos(5x) + C O - sin (5x) + C O None of the above