Activities to Teach Students the Inverses of Sin, Cos, and Tan: Radians

Trigonometry is a subject that deals with the relationship between the sides and angles of a triangle. It is a very important field of study, and one of the basic concepts of trigonometry is the inverse trigonometric functions. The inverse trigonometric functions are the inverse of sin, cos, and tan, and they are commonly used in engineering, physics, and other areas. Radians are also a critical concept in trigonometry, and their understanding is vital in teaching inverse trigonometric functions. In this article, we will discuss some activities that can be used to help students understand the inverses of sin, cos, and tan, as well as radians.

Activity 1: Introducing radian measure

Before you introduce the inverse functions, it’s essential to explain radians. Radian is a measure of an angle that’s based on the length of a radius of a circle. One radian corresponds to the angle that is formed by an arc of the circle whose length is equal to the length of the radius. To introduce this concept to the students, you can use a piece of string to measure the circumference of a circle and the length of one of its radii. Using this string, they can create different-sized angles in the circle (for example, one radian, two radians, etc.).

Activity 2: Using a unit circle

After the students understand radians, it’s time to introduce the unit circle. The unit circle is a circle with a radius of length 1 Unit. To help students understand the relationship of the unit circle with radians, ask them to draw a unit circle and mark on it all the angles in radians (for example, 0, pi/6, pi/4, pi/3, pi/2, etc.). Once the students have marked all the angles, they should draw lines from the center point to the circumference at each of these angles. These lines will form right triangles with one side equal to the radius, and the other two sides are the x and y coordinates of the point where the line intersects the circumference.

Activity 3: Introducing inverse sinus

Once the students understand radian measure and the unit circle, they are ready to learn about inverse trigonometric functions. Start with inverse sinus. Once they understand how to find the values of inverse sinθ using the unit circle, ask them to create their own problems. For example, you can ask them to find the value of sin x = ½. In this case, they would have to find the value of x on the unit circle and express it in radians.

Activity 4: Introducing inverse cosinus

After the successful completion of inverse sinus, inverse cosinus should be introduced. Begin by explaining the concept of cos and its inverse function. Once they’re familiar with it, use the unit circle to determine the values of inverse cosθ. This task can follow the pattern of Activity 3; for example, finding the value of cos x = sqrt(3)/2.

Activity 5: Introducing inverse tangent

Once the students have learned inverse sinus and inverse cosinus, it’s time to move on to inverse tangent. Use the unit circle to explain the relationship between the length of the sides of a right-angled triangle and its angle. Then, ask them to solve a problem involving the inverse tangent function. For example, the students could find the value of tan x = 3 /4 and express it in radians.


Teaching the inverse trigonometric functions can be challenging for students. However, with these activities, you can make it easier to understand the concept of radians and inverse functions. The key is to make the learning process interactive, and these exercises are a great way to achieve that. By using hands-on activities and practice problems, you can prepare your students to understand and use the inverse functions in the field of trigonometry.

Choose your Reaction!