设x = -3,y = -3则r = √ [(-3)² + (-3)²] = 3√2利用三角函数的定义:角α的正弦值:sinα = y / r = -3/ (3√2) = -√2/2角α的余弦值:cosα = x / r = -3/ (3√2) = -√2/2角α的正切值:tanα = y / x = ...