hoW to evaluate these if cos=-12/13, A in Q II and cot B =5/12, B in Q III
A) Sin^2 A
(the sign ^ is power of)
sin²A = (1-cos²A)
So if cosA=-12/13, then
sin²A
= 1-(-12/13)²
= 1-(144/169)
= 25/169
irrespective of the quadrant, since sin²A is required. If required, sinA is √(25/169)=5/13.