Tuesday

September 16, 2014

September 16, 2014

Posted by **TEETEE** on Thursday, October 25, 2012 at 9:27pm.

Sin(−5π/12)

- math -
**Reiny**, Thursday, October 25, 2012 at 10:26pmsome students have less difficulty if the angle is in degrees.

Let's try this approach ....

5π/12 radians = 75°

so sin(-5π/12)

= sin(-75°) which is in quadrant IV, making the sine negative

= -sin(75°)

= -sin(30° + 45°)

= -(sin30cos45 + cos30sin45)

= -( (1/2)(√2/2) + (√3/3)(√2/2) )

= - √2/4 - √6/4

so**sin(05π/12) = -√2/4 - √6/4**

check:

on my calculator:

sin(-5π/12) = -.9659...

and -√2/4 - √6/4 = -.9659..

My answer is correct

**Answer this Question**

**Related Questions**

Math - Use an addition or subtraction formula to write the expression as a ...

Precalculus - Use one of the identities cos(t + 2πk) = cos t or sin(t + 2&#...

Pre-Calc : Find the Exact Value of the Expression - Find the exact value of the ...

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

trig - Use an addition or subtraction formula to simplify the expression: tan(2...

MATH - 1.)Find the exact solution algebriacally, if possible: (PLEASE SHOW ALL ...

Math - Use the half formula to find the exact value of the expression sin 22.5

Math- Trig - 1. Determine the exact value of cos^-1 (pi/2). Give number and ...

Trig Help! - Question: Trying to find cos π/12, if cos π/6 = square ...

Math - If y = sin−1 x, then sin y = x,−π/2 ≤ y ≤ &#...