SOLUTION: We are having a hard time understanding why the Arcsin (-1) is -90 degrees. We know that the reference triangle is a 45,45,90 degree triangle. Sin is opp/adj so this makes no sense

Algebra ->  Trigonometry-basics -> SOLUTION: We are having a hard time understanding why the Arcsin (-1) is -90 degrees. We know that the reference triangle is a 45,45,90 degree triangle. Sin is opp/adj so this makes no sense      Log On


   



Question 826871: We are having a hard time understanding why the Arcsin (-1) is -90 degrees. We know that the reference triangle is a 45,45,90 degree triangle. Sin is opp/adj so this makes no sense to me. Please explain this for me.
Thanks ahead of time for helping me.
Caleb

Answer by rothauserc(4718) About Me  (Show Source):
You can put this solution on YOUR website!
The graph of the sine function depicts a periodic function which is not 1-1 unless we restrict the domain where the function is 1-1, the restriction is on the interval [-pi/2, pi/2] where pi is 180 degrees. Note that the x-axis is in radians (i.e. there are 2pi radians in a circle, 90 degrees is pi/2 radians)
+graph%28+300%2C+200%2C+-2.0%2C+2.0%2C+-2%2C+2%2C+sin%28x%29+%29+
We see that the graph of y = arcsin x is 1-1 over [-1, 1], y axis is in radians
+graph%28+300%2C+200%2C+-2.0%2C+2.0%2C+-2.5%2C+2.5%2C+asin%28x%29+%29+