cos^2 B - sin^2 B = 2 cos^2 B - 1
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Answer:
LHS = cos²B - sin²B
= cos²B - ( 1 - cos²B)
= cos²B -1 + cos²B
= 2cos²B -1 = RHS
HENCE proved
Step-by-step explanation:
formula used,
sin²∅ = 1 - cos²∅.
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