F4 trigonometry

suppose tanθ=2, find the value of (2sinθ+cosθ)/(sinθ-cosθ)
(2sinθ+cosθ)/(sinθ-cosθ)
=(2sinθ/cosθ +cosθ/cosθ)/(sinθ/cosθ-cosθ/cosθ)
=(2tanθ+1)/(tanθ-1)
=(4+1)/(2-1)
= 5

答得幾好! Why?

He can use trigonometric identical formula to solve this problem.

For example ,

1.sinθ/cosθ = tanθ

2. (sinθ^2)+(cosθ^2) = 1

總之 , 佢的解答很詳細 !

Very good !
Very well !
And very great !


In fact , trigonometric identical formula has 5 .

THESE THE 2 AMONG OF THEM .