Type the correct answer in each box Use numerals instead of words

Use stokes' theorem to evaluate c f · dr where c is oriented counterclockwise as viewed from above. f(x, y, z) = xyi + 5zj + 7yk, c is the curve of intersection of the plane x + z = 8 and the cylinder x2 + y2 = 81.

Asap! i need this done today and i really don’t understand it. some one ! will mark

What is the measure of angle a and angle c ?