Question

Triangle DEF is an isosceles, so AngleDEF Is-congruent-toAngleDFE. A horizontal line has points C, F, E, G. 2 lines extend from the line at points F and E to form an isosceles triangle with point D. Angle DEF measures 75°. What is the measure of angle CFD?

Answer 1

`\angle CFD =105^o`

Explanation:

Given

`\angle D FE = \angle DE F = 75^o`

See attachment

Required

Determine the measure of
`\angle CFD`

`\angle CFD` and
`\angle DFE` are on a straight line.

So:

`\angle CFD + \angle DFE = 180^o` --- angle on a straight line

Substitute known values

`\angle CFD + 75^o = 180^o`

Collect like terms

`\angle CFD =- 75^o + 180^o`

`\angle CFD =105^o`