Saturday

April 19, 2014

April 19, 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

**Related Questions**

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

Very easy math - my teacher told me that the inverse of addition was subtraction...

MATH 156 - What models can be used to help explain the concepts of addition and ...

math - 115-100+3*5= 115-100+3*5...Use BEDMAS (Bracket, Exponent, Division/...

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

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

math - How can you use subtraction to complete an addition pattern? use this ...

Math - use addition, subtraction, multiplication and/or division to make a ...

Math - Using the definition of subtraction to determine the subtraction ...

math - An eighth-grade student claims she can prove that subtraction of integers...