Use the cofunction identities and odd-even identities to prove that

MATHEMATICS · Subjective · A Level · Mathematics · Trigonometry · Trigonometry

Problem

90. Use the cofunction identities and odd-even identities to prove that cos⁡(π−x)=−cos⁡x\cos (\pi-x)=-\cos x. [Hint: cos⁡(π−x)=cos⁡(π/2−(x−π/2))\cos (\pi-x)=\cos (\pi / 2-(x-\pi / 2)).]

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