Question

найти cosx если sinx=15/17 0

Answer 1

sin(^2)x + cos(^2)x = 1
cos(^2)x = 1 - sin(^2)x
cos(^2)x = 1 - 225/289
cos(^2)x = 64/289
cos x = 8/17  
сos x = -8/17

Answer 2

соsx=√(1-sin^2x)
sun^2=125÷289
cos^2x=1-125÷289=64÷279
cosx=8\17