Question

Two interior angles of a triangle are of measures 80° and 40°. Find
the degree measure of the exterior opposite angle.

Answer 1

Answer:

I think its answer is 80 .

Step-by-step explanation:

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Answer 2

• One opposite exterior angle is 120°.

Step-by-step explanation:

Given:-

• Two interior angles of triangle are 80° and 40°.

To find:-

• Opposite exterior angle.

Solution:-

◆ By first method:-

We know that,

Sum of all interior angles of triangle is 180°

So,

➞ 80° + 40° + ∠1 = 180°

➞ 120° + ∠1 = 180°

➞ ∠1 = 180° - 120°

➞ ∠1 = 60°

We also know that,

Sum of all angles forms on straight line is equal to 180°. This statement is also known as linear pair.

So,

➞ ∠1 + ∠2 = 180°

➞ 60° + ∠2 = 180°

➞ ∠2 = 180° - 60°

➞ ∠2 = 120°

One opposite exterior angle of triangle is 120°.

◆ By second method:-

We know,

Sum of any two interior angles of triangle is equal to opposite exterior angle.

So,

➞ 80° + 40°

➞ 120°

One opposite exterior angle of triangle is 120°.