If for an acute angle

MATHEMATICS · Single correct · CBSE · Mathematics · Introduction to Trigonometry · Introduction to Trigonometry

Problem

If sin⁡A=k\sin A = k for an acute angle AA, which of the following correctly expresses cos⁡A\cos A in terms of kk? (a) 1−k21-k^{2} (b) 1−k\sqrt{1-k} (c) 1−k2\sqrt{1-k^{2}} (d) 1+k2\sqrt{1+k^{2}}

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