# Trig

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how do i find the exact value of s
[pie/2, pie]
sin s = radical2/ whole number 2

how do i figure this out without the use of a calculator. I drew the graph and located it in the second quadrant and i think the triangle is a 45-45-90 but i don't how to find the radians for the sin of s.

• Trig -

now divide this by simple whole numbers
e.g.
divide by 2 ---> π/2 = 90°
divide by 3 ---> π/3 = 60°
divide by 4 ---> π/4 = 45°
divide by 5 ---> π/5 = 36
divide by 6 ---> π/6 = 30°
divide by 8 ---> π/8 = 22.5°
etc.
copy this chart into a handy place in your notebook.

you know that the sine is positive in the first and 2nd quadrant.
Since s of sin s in in the second quadrant,
s = π - π/4 = 3π/4 , (180-45 = 135°)

check:
sin 3π/4 = .707106781... = √2/2

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