cosθ=7/25(cosθ)^2=7^2/25^2 1-(sinθ)^2=(cosθ)^2=7^2/25^2(sinθ)^2=1- (7^2/25^2)sinθ=-24/25(第四象限角）tanθ=sinθ/cosθ = (-24/25)/7/25 =- 24/7
