Final answer:
Angle DFE of isosceles triangle DEF is calculated to be 52.5°. The angle CFD, forming a straight line with angle DFE, is calculated to be 127.5°, with the closest option being 125°.
Step-by-step explanation:
In an isosceles triangle, the base angles are equal. Given that triangle DEF is isosceles, meaning angles DEF and DFE are equal. We know that the sum of the angles in a triangle is always 180°. So to find the measure of angle DFE, we subtract the known angle DEF (75°) from 180°, and divide the result by 2:
(180° - 75°) / 2 = 52.5°
Now, we know that a straight line makes an angle of 180°. Given that angle CFD is a straight line angle, to find the measure of angle CFD, we subtract the measure of angle DFE (52.5°) from 180°:
180° - 52.5° = 127.5°, so from your options listed, the closest one is 125°.
Learn more about Triangle Angles
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