SaiBook.us Geometry

Lesson Example Discussion Quiz: Class Homework

Example

Title: Angle(Types of angles)

Grade: 4-a Lesson: S2-L1

Explanation: The best way to understand geometry is by looking at some examples. Take turns and read each example for easy understanding.

Examples:

The difference between the two supplementary angles is 42°.Find both angles.

Step 1a

The sum of two supplementary angles is equal to 180°.

$1a$

Explanation: When two angles are supplementary, their sum equals 180°.

Step 1b

Let us assume one angle is (180 - x)° and second angle be x°.

Explanation: Let’s assume that one angle measures (180 - x)° and the other angle measures x°.

Step 1c

The given text highlights a difference., 42°

Therefore (180 - x)° - x ° = 42°

After simplification 180° - 2x = 42°

⇒ 180° - 42° = 2x

⇒ 2x = 138°

Then x value is 69°

The second angle is 180° - 69° = 111°

Explanation: To find two angles when one angle is 42° more than the other, we can use the equation 180° - 2x = 42°. After simplification, we get x = 69° and the larger angle is 111°.

Step 1d

So, the two supplementary angles are:

Angle A = 69°

Angle B = 111°

Explanation: So we’ve got two angles here that add up to 180°. The first one measures 69°, and the second one is 111°.