I need help on this page ASAP 15 points

What basic trigonometric identity would you use to verify that csc x sec x cot x = csc^(2)x

Which statement justifies why angle ebc measures 90?

How is the equation of this circle written in standard form? x2 + y2 - 6x + 14y = 142 a) (x - 3)2 + (y + 7)2 = 200 b) (x+ 3)2 + (y - 7)2 = 200 (x - 6)2 + (y + 14)2 = 142 d) (x+6)2 + (y- 14)2 = 142