Tuesday

July 22, 2014

July 22, 2014

Posted by **Lucy X** on Sunday, December 7, 2008 at 2:34am.

How do I get started on this question?

- Math -
**Damon**, Sunday, December 7, 2008 at 5:30amThis angle x is obtuse, between 90 and 180 degrees. Therefore 2x is between 180 and 360.

tan x = -3/4

height = 3

base = 4

hypotenuse = 5 (3,4, 5 right triangle)

so

sin x = 3/5

cos x = -4/5

and we know sin 2x = 2 sin x cos x

so

sin 2x = 2(3/5)(-4/5)

sin 2x = -24/25

- Math -
**drwls**, Sunday, December 7, 2008 at 5:36amAngles with negative values of the tangent are in the second or fourth quadrant. If it is obtuse (between 90 and 180 degrees), it is in the second quadrant. The supplement of the angle is sin^-1 (3/5)= 36.87 degrees. (Think of a 3,4,5 right reference triangle). The angle x is therefore 143.13 degrees, and its sine is 3/5. Its cosine is -4/5. Use sin 2x = 2 sin x cos x to get the sine of twice the angle.

Sin (2x) = 2(3/5)(-4/5) = -24/25 = -0.96. It is in the fourth quadrant.

**Related Questions**

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

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

mathematics - evaluate each of the following..sin 130.tan 60/cos 540.tan 230.sin...

Math - Evaluate *Note - We have to find the exact value of these. That I know to...

Inverse Functions & Trig. Equations - 7. Evaluate sin[sin^-1(-1/2)]. a. 1/2 b...

MathsSs triG - Consider sin(x-360)sin(90-x)tan(-x)/cos(90+x) 1.A.SIMPLIFY sin(x-...

Limit Calculas - Evaluate lim->4 sin(2y)/tan(5y) Here is what I have so far. ...

calculus - Evaluate lim->4 sin(2y)/tan(5y) Here is what I have so far. I am ...

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

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