Wednesday

April 23, 2014

April 23, 2014

Posted by **t54** on Monday, April 4, 2011 at 6:17pm.

tan(165)

- advanced math -
**Reiny**, Monday, April 4, 2011 at 7:31pmI bet it said "find the exact value"

sin(-15) = sin(30-45)

= sin30cos45 - cos30sin45

= (1/2)(√2/2) - (√3/2)(√2/2) = (√2 - √6)/4

tan(165) = tan(120+45)

= (tan120 + tan45)/(1-tan120tan45)

tan 120 = -tan60 = -√3

so back into the above result

= (-√3 + 1)/(1 - (-√3)(1)) = (1-√3)/(1+√3)

**Related Questions**

precalculus - For each of the following determine whether or not it is an ...

Trig - Given: cos u = 3/5; 0 < u < pi/2 cos v = 5/13; 3pi/2 < v < ...

Trigonometry - 1.Solve tan^2x + tan x – 1 = 0 for the principal value(s) to two ...

trig - how do i solve tan(165) and sin(285)

Trigonometry desperate help, clueless girl here - 2. solve cos 2x-3sin x cos 2x...

Maths Calculus Derivatives - Find the first derivative for the following ...

Trig Identities - Proving identities: 1) 1+ 1/tan^2x = 1/sin^2x 2) 2sin^2 x-1 = ...

TRIG - what is another form of: sin (A+B) sin (A-B)/ cos^2 A cos^2 B a) cos^2 A...

math - Prove these identites I really need help with these I dont understand ...

math - Prove these identites I really need help with these I dont understand how...