a) Prove the Identity cot 1/2 A - tan 1/2 A = 2cotA

b) By choosing a suitable numerical value for A, show that tan15 is a root of the quadratic equations t^2 + 2 sqrt.3t -1 = 0

thanks.

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- Dec 2nd 2009, 07:28 AMOasis1993Proving identities
a) Prove the Identity cot 1/2 A - tan 1/2 A = 2cotA

b) By choosing a suitable numerical value for A, show that tan15 is a root of the quadratic equations t^2 + 2 sqrt.3t -1 = 0

thanks. - Dec 2nd 2009, 07:49 AMqmech
Let B = A/2

- Dec 2nd 2009, 07:51 AMmrmohamed
- Dec 2nd 2009, 07:54 AMmrmohamed
- Dec 2nd 2009, 08:08 AMmathaddict