我想我唔俾答案你...俾d hints你...你睇下做唔做到...
1. cos60 = sin(90-60) =sin30, tan 30 =sin30/cos30
2. tan x = sin x/cos x, tan x/cos x簡代完只餘sin x, a及b唔洗用畢氏定理都找到。
3. tan x = sin x/ cos x, 約完搬完就變sin x = 1/root2 =>x應該是45
4. 唔記得點做...
5. cos(90-x)=sin x, sin(90-x) = cos x; 將d加埋等於90的數合埋一齊, 再將度數變埋一樣就運算到。
6. cos (90-x)=sin x, tan(90-x) = 1/tan x