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(cos²x - sin²x) / (cos²x + sinxcosx) = 1 - tanx
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use a² -b² = (a+b)(a-b) for the numerator
take cosx common from the denominator
cancel off the common factor and then
divide term by term
answer and some steps are given below
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(trig. formulae)
some other examples
prove that (cotA+cosecA-1)/(cotA-cosecA+1)=cosecA+cotA -----> (problem on trigonometry )
Prove that (tanxsinx) / (tanx+sinx) = (tanx-sinx) / (tanx sinx) -----> (problem on trigonometry )
find exact value of tan[22½ °] or tan (pi / 8 ) -----> (problem on trigonometry )
conditional identity : If A+B+C=π,
prove that: sinA+sinB+sinC = cot(A/2).cot(B/2) [sinA+sinB-sinC] -----> (problem on conditional identity (trigonometry) )
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formulae on sequences and series
(trig. formulae)
(integration formulae)
(other math problems without classification) or problem index
(formulae on differentiation)
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