How to Find Angle?

Wait!

We have learned about six trigonometric ratios.

Still the question remains – how do we find

measure of angle A?

Earlier, we had trigonometric tables to read the value. Now it is much simpler. Scientific Calculators can help us. Keys of our interest are enlarged and shown.
Identify the trigonometric ratio keys on your calculator. With Shift key these trigonometric functions return the angle for the given value.
Change mode to Degrees for this unit. Radian is default unit for angle measurements. However, we will focus only in degree for Part I of trigonometric.

In the  we are given opposite side, and adjacent side . Tangent ratio relates these two sides and therefore we can use it to find the measure of angle A. Inverse trigonometric ratio is used to find measure of angle.

Check the result:

18749

because of rounding.

Four decimal places is recommended for accurate results.