AP EAMCET · Maths · Trigonometric Ratios & Identities
\(\cos ^2 45^{\circ}+\cos ^2 135^{\circ}+\cos ^2 225^{\circ}+\cos ^2 315^{\circ}=\)
- A 1
- B 2
- C 0
- D -1
Answer & Solution
Correct Answer
(B) 2
Step-by-step Solution
Detailed explanation
\begin{aligned} & \cos ^2 45^{\circ}+\cos ^2 135^{\circ}+\cos ^2 225+\cos ^2 315^{\circ} \\ &=\cos ^2 45^{\circ}+\cos ^2\left(180^{\circ}-45^{\circ}\right)+\cos ^2\left(180^{\circ}+45^{\circ}\right) \\ &+\cos ^2\left(360^{\circ}-45^{\circ}\right) \\ &= 4 \cos ^2…
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