Explain limitation of algebra that leads development of calculus and how?

How do you answer this question? (step by step)

Write the expression as a constant , a single trigonometric function, or a power of a trigonometric function. sin x cos x/ tan x

If the endpoints of the diameter of a circle are (8, 6) and (2,0), what is the standard form equation of the circle? a) (x + 5)2 + (y + 3)2 = 18 (x + 5)2 + (y + 3)2 = 3.72 (x - 5)2 + (y - 3)2 = 18 d) (x - 5)2 + (y - 3)2 = 32