Question

cos2 0°+cos2 60°+cos2 90° ​

Answer 1

Answer:

$\huge\boxed{\bf \implies \frac{3}{2} }$

Step-by-step explanation:

$\bf \:{ cos}^{2}0°+{cos }^{2}60°+{cos}^{2}90° \\ \\ \bf \implies {1}^{2} + { \frac{1}{2} }^{2} + {0}^{2} \\ \\ \bf \implies \frac{2 + 1 + 0}{2} \\ \\ \boxed{\bf \implies \frac{3}{2} }$

Answer 2

Answer:

$cos(0) = 1 \\therefore \: \cos2(0) = \: 2 \\ \cos(60) = \frac{1}{2} \\ therefore \: \cos2(60) = \: \frac{1}{2} \times 2 = 1 \\ \cos(90) = 0 \\ therefore \: \cos2(90) = 0 \\ therefore \: \cos2(0) \: + \cos2(60) \cos2(90) \\ = 2 + 1 + 0 \\ = 3$

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