If sin a + cosec a = 2, show that sin^7 a + cosec^7 a = 2
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Sin⁷a + Cosec⁷a = 2
Step-by-step explanation:
If sin a + cosec a = 2, show that sin^7 a + cosec^7 a = 2
Sina + Coseca = 2
Coseca = 1/Sina
=> Sina + 1/Sina = 2
Multiplying by sina both sides
=> Sin²a + 1 = 2Sina
=> Sin²a - 2Sina + 1 = 0
=> (Sina - 1)² = 0
=> Sina - 1 = 0
=> Sina = 1
Cosec = 1/Sina = 1
LHS
= Sin⁷a + Cosec⁷a
= 1⁷ + 1⁷
= 1 + 1
= 2
= RHS
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