Q15 of 90 Page 7

prove that:

cos2 π/4 - sin2

LHS


We know that cos2A – sin2B = cos(A +B) cos(A –B)






= RHS


Hence, proved.


More from this chapter

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14

If tanA = 5/6 And tanB = 1/11, prove thatA +B = π/4.

 14

If tanA = m/m–1 And tanB = 1/2m – 1, then prove that A –B = π/4.

 15

prove that:

sin2(n + 1)A – sin2nA = sin(2n + 1)A sinA

 16

Prove that: