How can I prove these statements to be true??
1. Sin^-1(sin (theta))=theta
2. cos(cos^-1 x)=x
Algebra 2/ Trig?
2015-08-27 11:51 pm
回答 (1)
2015-08-28 12:56 am
✔ 最佳答案
Actually, the first one is false. We just need one counterexample to prove it.sin^-1(sin(9pi/4)) = pi/4
cos(cos^-1(x)) is true.
The range of cosx, [-1,1], is the same as the domain of cos^-1(x), [-1, 1] so cos(cos^-1(x)) will always return x.
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