Unit A: Geometry

Chapter 3: Trigonometry

Finding the Sine of an Angle Using a Calculator


Before the sine law is studied, it is important to review how to find the sine of an angle using a calculator. The two most common modes for measuring angles are degrees (DEG) and radian (RAD). For Math 30-3, it is really important that the calculator is in degree mode. Many calculators have a mode button to change the setting to degree mode. In non-graphing calculators, DEG will appear on the screen. If you need help setting your calculator to degree mode, contact your teacher.

It is important to make sure that the sine of an angle can be calculated properly using a calculator. The two most common ways to find the sine of an angle are

Method 1:
Step 1: Press .
Step 2: Type in the angle measure.
Step 3: Press the equals sign.
Method 2:
Step 1: Type in the angle measure.
Step 2: Press .
Step 3: Press the equals sign.

Test your calculator using sin 48°. Determine which method correctly calculates sin 48° on your calculator.

Method 1:
Step 1: Press .
Step 2: Type in 48.
Step 3: Press the equals sign.
Method 2:
Step 1: Type in 48.
Step 2: Press .
Step 3: Press the equals sign.

The correct method will result in the number 0.7431 appearing on your calculator.

Note: Sine values are generally written to four decimal places.
The sine of an angle is between 0 and 1.