Geometry

# Fundamental Trigonometric Identities: Level 2 Challenges

Find the value of

$\cos^2 45^{\circ} +\sin^2 45^{\circ}.$

Simplify $$\tan\left(A + \frac{\pi}{2}\right).$$

If $$\sin A +\sin^{2}A=1,$$ find the value of $$\cos ^{2} A + \cos ^{4} A.$$

$\ln(\tan1^{\circ})+ \ln(\tan2^{\circ})+\ldots+\ln(\tan88^{\circ})+\ln(\tan89^{\circ})= \ ?$

What is the value of $$\sin 20^{\circ}(\tan 10^{\circ}+\cot 10^{\circ})$$?

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