Question

已知角α的终边经过P(x,-√2)(x≠0),且cosα=√3/6,求sinα,tanα的值

Answer 1

α的终边经过P(x,-√2)(x≠0),故位于y负半轴（三四象限）

sinα = - sqrt(1-cos²α) = - sqrt (1- (√3/6)²) = -√(11/12)

tanα = sinα/cosα = -√(11/12) / √3/6 = - √11