Friday

February 27, 2015

February 27, 2015

Posted by **Yulieth** on Sunday, November 20, 2011 at 7:18pm.

a. cos(-θ)

b. cos(11π/6 - θ)

c.sin2θ

d.tanθ/2

can some please explain to me how to solve these questions? thanks

- trigonometry -
**Steve**, Sunday, November 20, 2011 at 10:55pmThe angle is in the 2nd quadrant, so x is negative, and y is positive. The hypotenuse has length 7.

So, since tanθ = -2√10/3,

y = 2√10

x = -3

sinθ = y/h = 2√10/7

cosθ = x/h = -3/7

Use these values in your double-angle, half-angle and sum/difference formulas

**Answer this Question**

**Related Questions**

Precalc/Trig - Sorry there are quite a few problems, but I just need to know if ...

trigonometry - given tanθ= -2√10/3 and π/2<θ< π ...

trigonometry - if cosθ=2/3 and tanθ<0 find the exact value sin(&#...

trig - cosθ =5/13 with -π/2 < θ <0 find each of the ...

math - if cosθ=2/3 and tanθ<0 find the exact value sin(θ-5&#...

Math - Calculus - The identity below is significant because it relates 3 ...

Trigonometry - Which of the following is equivalent to 1 − cos 2 θ/...

math - given sinθ=-5/13 and π<θ<3π/2 find sin2θ ...

mathematics - given sinθ=-5/13 and π<θ<3π/2 find sin2...

mathematics - given tanθ= -2√10/3 and π/2<θ< π ...