Question

Find the missing angle measure for each triangle, then classify each triangle as isosceles or not isosceles. (Look at attachment)

Answer 1

The measurement of the missing angle for each triangle is:

1. 65 ° Not isosceles

2. 60 ° Not isosceles

3. 55 ° isosceles

How to calculate the missing angle?

Isosceles triangle is a triangle having two sides or two of its angle equal.

The measurement of the missing angle for each triangle can be calculated as follow:

For diagram 1

Angle present in the diagram are:

• 60 °
• 55 °
• Missing angle =?

60 + 55 + missing angle = 180

115 + missing angle = 180

Collect like terms

Missing angle = 180 - 115

= 65 ° isosceles

For diagram 2

Angle present in the diagram are:

• 60 °
• 60 °
• Missing angle =?

60 + 60 + missing angle = 180

120 + missing angle = 180

Collect like terms

Missing angle = 180 - 120

= 60 ° Not isosceles

For diagram 3

Angle present in the diagram are:

• 70 °
• 55 °
• Missing angle =?

70 + 55 + missing angle = 180

125 + missing angle = 180

Collect like terms

Missing angle = 180 - 125

= 55 ° isosceles