Question

Determine the missing angle in a triangle.

Answer 1

?=145°

Explanation:

The angle 137° is a supplementary angle. So subtract 137 from 180 to find the adjacent angle:

`180-137=43`

The angle adjacent the angle 137° is 43°. Add this value to the angle measure in the triangle:

`102+43=145`

Two angle measures within the triangle add up to 145°. The angle measures of a triangle should add up to 180°. Subtract:

`180-145=35`

The third angle in the triangle is 35°. This angle is also a supplementary angle. Subtract this from 180 to find the measure of angle ?:

`180-35=145`

The angle ? is 145°.

or

The outer angle of a triangle (angle ?) can be found by finding the sum of the two angles within a triangle, not including the adjacent angle (or ?'s supplementary angle). So find the measure adjacent 137°:

`180-137=43`

Add the two inner angle measure together:

`43+102=145`

So angle ? is 145°.

:Done

Answer 2

145

Explanation:

The the that connects the outside line to the inside line will equal to 180 so you take 180 minus 137 to get 43 and you have two angles for the inside which is 43 and 102. You minus these two number to 180 to get the last missing angle in a triangle because the inside of a triangle is 180 and then minus 180 to 35(Last angle measure) to get the outside of the triangle and you get 145.