- #1

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Sum Formula for Tangant: Tan (a+b) = Tan a + Tan b/1-Tan a * Tan b

Problem: Find the

*exact*value,

Tan 15 + Tan 30/1- Tan 15 * Tan 30

Correct answer: -1

but I can't seem to get the answer in the end; are the tangants in the numerator added to make tan 45 then solved for? If not, how would you express tan 15 in an exact form? Similarly, how do you multiply tan 15 and tan 30? Or am I missing some other identity?

Its been driving me crazy all day!