Calculate: a) cos^2(5 pi/6) sin(7 pi/8)^2 + tan(pi/6 ln 8)/squareroot 7 b) cos(5 pi/6)^2 sin^2(7 pi/8) + tan(pi ln 8/6)/7 middot 5/2 Use the built-in function "pi" for al1 your equations