Math, asked by ohnoomg87, 1 month ago

please refer to image

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Answered by NONGAMBA
0

Answer:

2

Step-by-step explanation:

3- Cos²(72°)-Cos²(18°)

=> 3-Cos²(90°-18°) - Cos²(18°)

=>3 - Sin²(18°) - Cos²(18°)

=>3-[Sin²(18°) + Cos²(18°)]

Since, Sin²x + Cos²x = 1

Therefore, 3-[Sin²(18°) + Cos²(18°)] = 3-1 = 2

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