Could anyone give me some hints? I can't think the first step~

Given that ,

,

express the following in therms of a and b:

(a) cos (x - y)

(b) sin (x - y)

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- April 17th 2006, 08:27 AMling_c_0202express cos (x - y)
Could anyone give me some hints? I can't think the first step~

Given that ,

,

express the following in therms of a and b:

(a) cos (x - y)

(b) sin (x - y) - April 17th 2006, 08:50 AMThePerfectHackerQuote:

Originally Posted by**ling_c_0202**

Thus,

Thus,

Thus,

Thus,

Thus,

- April 17th 2006, 08:58 AMrgep
Try multiplying each relation by and adding and subtracting.

- April 18th 2006, 09:16 AMling_c_0202
Thank you very much!! ^^