Is there an easy way i can find the related acute angle(reference angle) when give any degree? If not then can u tell me a method that is proper so that i can do good on reference angle

1 Answer
Apr 10, 2015

The method I teach is to draw the angle in standard position and the figure out how big the positive angle between the terminal side and the horizontal is.

I'm not sure what would be easier, but here's a numerical method. (One you could program a computer to do.)

For angle A given in degrees, If A >= 360, find A_1 = A-360

If A_1 >= 360, find A_2 = A_1 - 360

Continue until you get an angle A_n < 360

Call the reference angle R. and apply the four part rule:

If 0 <= A_n <= 90, then R = A_n
If 90 < A_n <= 180, then R = 180 - A_n
If 180 < A_n <= 270, then R = A_n - 180
If 270 < A_n < 360, then R = 360 - A_n

Not everyone will find this easier, but it does not require drawing a picture of the angle.