cos2∏\11+cos4∏\11+cos6∏\11+cos8∏\11+cos10∏\11=?
the value is a rational
]]>tan.tan.cos=(sin.sin)\(cos.cos)\cos
=(sin.sin)\cos
=(sin\cos).sin
=tan.sin
(1-tan)\(1+tan)=(cot-1)\(cot+1)
cot+1-tan.cot-tan=cot-1+tan.cot-tan
so 1-tan.cot=tan.cot-1
2=2tan.cot
tan.cot=1
=[(sin+cos)\cos]\[(sin-cos)\cos]
=(sin+cos)\(sin-cos)
so (sin+cos)\(sin-cos)=(sin+cos)\(sin-cos)
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4. If 3 tanθ = 4, determine the value of
5. If 5cosθ-12sinθ=0, what is the value of
6. If 16cotA=12, find the value of
7. Prove that
8. Prove that
9. Prove that
10. Prove that