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Question
Prove the following:
`(tan5"A" - tan3"A")/(tan5"A" + tan3"A") = (sin2"A")/(sin8"A")`
Sum
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Solution
L.H.S. = `(tan5"A" - tan3"A")/(tan5"A" + tan3"A")`
= `((sin5"A")/(cos5"A") - (sin3"A")/(cos3"A"))/((sin5"A")/(cos5"A") + (sin3"A")/(cos3"A"))`
= `(((sin5"A" cos3"A" - sin3"A" cos5"A")/(cos5"A" cos3"A")))/(((sin5"A" cos3"A" + sin3"A" cos5"A")/(cos5"A" cos3"A"))`
= `(sin5"A" cos 3"A" - cos5"A" sin3"A")/(sin5"A" cos3"A" + cos5"A" sin3"A")`
= `(sin(5"A" - 3"A"))/(sin(5"A" + 3"A"))`
= `(sin2"A")/(sin8"A")`
= R.H.S.
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Chapter 3: Trigonometry - 2 - Exercise 3.1 [Page 39]
