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NCERT Class XI Mathematics - Trigonometric Functions - Solutions

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Question : 21
Total: 61
2sin2
3π
4
+2cos2
π
4
+2sec2
π
3
 = 10
Solution:  
L.H.S. = 2sin2
3π
4
+2cos2
π
4
+2sec2
π
3
= 2sin2(
4π−π
4
) + 2 × (
1
√2
)2 + 2 × (2)2 = 2sin2(π−
π
4
) + 2 ×
1
2
 + 8
= 2sin2
π
4
+1+8 = 2 × (
1
√2
)2 + 9 = 10 = R.H.S.
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