Posted by jaden on Thursday, February 26, 2009 at 9:21pm.
how do i solve
trig - Reiny, Thursday, February 26, 2009 at 9:40pm
the instructions probably say:
evaluate the exact value of ....
that means, you do not use a calculator.
(That does not mean we cannot use one to check the answer we find)
the trick for all of these is to split the given angle into two or more parts whose trig values we know
so tan(165) = tan(90+75) or tan(180-15) or ...
let's use tan(180-15)
= -tan 15 , (I know that from my CAST properties)
now we have to find tan 15
= (tan45 - tan30)/(1 + tan45tan30)
= (1 - 1/√3)/(1 + 1/√3)
= (√3 - 1)/(√3 + 1)
= -tan15 = (1 - √3)/(√3 + 1)
for the second one, sin285,
I would use sin(360-75)
= - sin75
then use 45 and 30 and the sin(A+B) expansion.
check your answer with your calculator,
I did my first result, and I am right.
Answer This Question
More Related Questions
- Trigonometry - use the appropriate trig identity (sum and difference, half angle...
- Trig - Given: cos u = 3/5; 0 < u < pi/2 cos v = 5/13; 3pi/2 < v < ...
- trig 26 - simplify to a constant or trig func. 1. sec ²u-tan ²u/cos ²v+sin ²v ...
- MathsSs triG - Consider sin(x-360)sin(90-x)tan(-x)/cos(90+x) 1.A.SIMPLIFY sin(x-...
- Trig Identities - Proving identities: 1) 1+ 1/tan^2x = 1/sin^2x 2) 2sin^2 x-1 = ...
- Trig - can I please have help with these 3 questions? 1. Solve this equation ...
- Math-Trig - 1. Create an algebraic expression for sin(arccosx-arcsin3x) 2. The ...
- Trigonometry desperate help, clueless girl here - 2. solve cos 2x-3sin x cos 2x=...
- TRIG - what is another form of: sin (A+B) sin (A-B)/ cos^2 A cos^2 B a) cos^2 A...
- Trigonometry - 1.Solve tan^2x + tan x – 1 = 0 for the principal value(s) to two ...