Finding missing angles in special triangles can be a challenging task for students. However, it is an essential skill that they need to acquire, especially when studying geometry. Here are some activities that teachers can use to teach their students how to find missing angles in special triangles.

**Activity 1: Identifying Special Triangles**

Before students can find the missing angles in special triangles, they need to know what special triangles are. In this activity, students will learn to identify three types of special triangles – the equilateral triangle, the isosceles triangle, and the right-angled triangle.

To begin, the teacher can create a chart with pictures of the three types of special triangles and their properties. The students can then match the pictures to the correct properties by working in groups.

After identifying the properties, the teacher can provide examples of each type of special triangle and ask students to identify which type it belongs to. This activity will help students become familiar with different types of special triangles, which will aid in finding missing angles in the next activities.

**Activity 2: Finding Missing Angles in Equilateral Triangles**

Equilateral triangles are special triangles because they have three equal sides and three equal angles. In this activity, students will learn how to find the missing angle in an equilateral triangle.

The teacher can give each student an equilateral triangle and ask them to find the measure of each angle. They can use a protractor to measure the angles or use the formula for finding the measure of angles in an equilateral triangle, which is 180 degrees divided by 3.

Once the students have found the measure of each angle, the teacher can then ask them to find the missing angle. The missing angle in an equilateral triangle is always 60 degrees since all angles are equal.

**Activity 3: Finding Missing Angles in Isosceles Triangles**

Isosceles triangles are special triangles because they have two equal sides and two equal angles. In this activity, students will learn how to find the missing angle in an isosceles triangle.

The teacher can give each student an isosceles triangle and ask them to find the measure of each angle. They can use a protractor to measure the angles or use the formula for finding the measure of angles in an isosceles triangle, which is (180 degrees – the unequal angle) divided by 2.

Once the students have found the measure of each angle, the teacher can then ask them to find the missing angle. To find the missing angle in an isosceles triangle, the students need to subtract the sum of the other two angles from 180 degrees.

**Activity 4: Finding Missing Angles in Right-Angled Triangles**

Right-angled triangles are special triangles because they have one angle that measures 90 degrees. In this activity, students will learn how to find the missing angle in a right-angled triangle.

The teacher can give each student a right-angled triangle and ask them to find the measure of each angle. They can use a protractor to measure the angles or use the Pythagorean theorem to find the missing angle, which is the angle opposite the longest side.

Once the students have found the measure of each angle, the teacher can ask them to find the missing angle by using the fact that the sum of the two other angles in a right-angled triangle must be 90 degrees.

**Conclusion**

Teaching students to find missing angles in special triangles requires hands-on activities that enable them to work independently and collaboratively. By doing various activities, students will develop critical thinking skills, become familiar with different types of special triangles, and learn how to use different formulas to find missing angles. Therefore, teachers should incorporate these activities in their lesson plans to help their students master the concept of finding missing angles in special triangles.