Use the image to answer the question.

A circle has center point upper O. Points upper D, upper E, upper F, and upper G are plotted on the circumference of the circle and joined by lines.

If m∠FOG=105 degrees, then what is the measure of ∠FOD ?

(1 point)
Responses

85 degrees
85 degrees

75 degrees
75 degrees

37.5 degrees
37.5 degrees

150 degrees

1 answer

To find the measure of angle ∠FOD given that m∠FOG = 105 degrees, we can use the properties of angles in a circle.

In a circle, the angle formed by two lines from the center of the circle to points on the circumference is called a central angle. The angle subtended at any point on the circumference by this central angle is called an inscribed angle.

In this case, we need to find the angle ∠FOD. The angle ∠FOG is an angle at the center of the circle, and it subtends the arc FG. Therefore, the inscribed angle ∠FOD will be half of the central angle ∠FOG, since the inscribed angle is always half of the central angle that subtends the same arc.

So, we have: \[ m∠FOD = \frac{1}{2} m∠FOG = \frac{1}{2} (105 \text{ degrees}) = 52.5 \text{ degrees} \]

However, none of the given options seem to include 52.5 degrees.

This could indicate an incorrect premise or ambiguity in the angles that are supposed to be compared to. Given the provided choices and common circumstantial setups in this situation, the angle ∠FOD might instead relate to different parts of the circle.

If we consider the entire arc FG and the measure of the central angle FOG as 105 degrees, we can find the reflex angle FOD, which can generally be calculated by: \[ m∠FOD = 360° - m∠FOG = 360° - 105° = 255° \text{ (which is outside of our options)} \]

Instead, let’s factor back to the relationships and reconsider:

In the circle established, angle FOD derived but through direct inversion likeliness through smaller arc FGD would theoretically result in: \[ m∠FOD = 75° \quad (Since 180° - 105° = 75°) \]

Thus the answer to the originally asked angle measure ∠FOD could also pragmatically yield to the closest accessible edge compare relation, leading us to answer:

75 degrees.