Find the exact values (precalc)

Question

Find the exact values (fractions) for the trigonometric expression given that sin u = 4/5 and cos v = -7/25 (both u and v are in II quadrant)

Answer 1

sinu = 4/5

u=sin^-1(4/5) = about 180-53.13 = 126.87 + 360n where n= any integer

for a more exact solution u= 126.8698976...+360n

there is no perfectly exact solution, just as close as the number of decimals your calculator provides

cosv=-7/25 = 106.2602047 + 360n degrees, where n= any integer