Suppose sin(B)=.75. Calculate cos(A)
We use the formula (sinB)^2 + (cosB)^2 = 1;But, sinB = 3/4;Then, (cosB)^2 = 1 - 9/16;(cosB)^2 = 7/16;cosB = + or - √7 / 4;
SinB = 0.75 Recall: Sin²B + Cos²B = 10.75² + Cos²B = 10.5625 + Cos²B = 1Cos²B = 1 - 0.5625 Cos²B = 0.4375CosB = + or -√0.4375Cos B ≈ + or -0.6614
