Triangle Angles and Combining Like Terms

This lesson teaches how to find the measure of an angle in a triangle using the other two angles. It explains that the sum of angles in a triangle is 180 degrees and reviews combining like terms in expressions. Common mistakes, such as thinking the sum is 90 degrees, are addressed. The lesson includes examples of finding angles in triangle ABC, using both numerical values and expressions. The conclusion summarizes the key points learned.

What is the sum of all angles in a triangle?

• 90 degrees

• 180 degrees

• 360 degrees

• 270 degrees

What is the first step in combining like terms?

• Rewrite terms so like terms are next to each other

• Subtract the smallest term

• Multiply all terms by 2

• Add all numbers together

Which of the following is a common mistake students make about triangle angles?

• Thinking the sum is 180 degrees

• Thinking the sum is 360 degrees

• Thinking the sum is 90 degrees

• Thinking the sum is 270 degrees

In a right triangle, if one angle is 90 degrees, what can be said about the other two angles?

• They must be less than 45 degrees each

• They must be equal

• They must add up to 180 degrees

• They must add up to 90 degrees

How do you set up an equation to find an unknown angle in a triangle?

• Multiply all angles by 2

• Subtract known angles from 180

• Add all angles and set equal to 90

• Add all angles and set equal to 180

If angle A in triangle ABC is represented as x + 11, and x is found to be 29, what is the measure of angle A?

• 11 degrees

• 68 degrees

• 40 degrees

• 29 degrees

What is the first step in solving for an angle when given expressions for each angle?

• Subtract the smallest expression

• Add all coefficients

• Set the sum of expressions equal to 180

• Set the sum of expressions equal to 90

When combining like terms, what do you do after rewriting the terms?

• Divide the coefficients of like terms

• Multiply the coefficients of like terms

• Subtract the coefficients of like terms

• Add the coefficients of like terms

If the angles of a triangle are given as x, 2x, and 3x, what is the value of x?

• 45

• 90

• 60

• 30

What is the measure of angle B if angles A and C are 47 and 65 degrees respectively?

• 90 degrees

• 65 degrees

• 47 degrees

• 68 degrees