1.solve (sin x+ cos x )^2 = 2sin(π/4+x)sin(π/4-x)
for 2π≧x≧0
2.in ⊿ABC
a) show that sin A=sin(B+C)
b) suppose that tan B= cos(B-C)/(sinA-sin(B-C))
i)show that cos B cos (B+C)= 0
ii)hence , prove that A=π/2
3.given cos(θ+α)=p and sin(θ+β)=q
a)express cosθ and sinθ in terms of α, β, p, q
b)hence, show that p^2+q^2+2pq sin(α-β)=cos^2(α-β)
compound angles question
2009-08-11 6:34 pm
回答 (1)
2009-08-11 8:56 pm
✔ 最佳答案
As follows:圖片參考：http://i707.photobucket.com/albums/ww74/stevieg90/01-52.gif
圖片參考：http://i707.photobucket.com/albums/ww74/stevieg90/02-48.gif
圖片參考：http://i707.photobucket.com/albums/ww74/stevieg90/03-43.gif
2009-08-12 15:51:05 補充：
Sorry for making mistake...
cos2x-sin2x=1
√2cos(2x+pi/4)=1
cos(2x+pi/4)=1/√2
2x+pi/4=pi/4 , 7pi/4 , 9pi/4
x=0 , 3pi/4 , pi
收錄日期: 2021-04-11 01:03:02
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20090811000051KK00463