Please Help!

For tan 15 degrees

Since Tan 45-tan 30=tan 15

i got this

1-1/√3 as the exact answer but books answer is (√3-1/√3+1)

what am i doing wrong?

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- Apr 6th 2009, 09:01 AMjepalfind exact values of Tan 15 degrees and Cos 75 degrees
Please Help!

For tan 15 degrees

Since Tan 45-tan 30=tan 15

i got this

1-1/√3 as the exact answer but books answer is (√3-1/√3+1)

what am i doing wrong? - Apr 6th 2009, 09:15 AMstapel
Um... not actually. The value of tan(15) is the same as the value of tan(45 - 30), but not at all the same as the value of tan(45) - tan(15)! (Surprised)

Are you familiar with**function notation**at all? If so, then note that the tangent function is a*function*, so "tan(x)" means "f(x)", where the specific name of the function "f" is "tangent". Just as f(a + b) does*not*mean the same thing as f(a) + f(b), so also tan(45 - 30) does*not*mean tan(45) - tan(30).

To simplify tan(45 - 30), you have to use the angle-difference formula they gave you. (Wink) - Apr 6th 2009, 09:19 AMjepal