The moon has a diameter of 3

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The moon has a diameter of 3.48 x 10^6 m and is a distance of 3.85 x 10^8m from the earth. The sun has a diameter of 1.39 x 10^9 m and is 1.50 x 10^11 m from the earth.
(a.)Waht are the angles (in radians) subtended by the moon and the sun, as measured by a person standing on the earth.

The angle in radians is measured by the ratio of arc length to the radius. Hence the angle subtended by the moon at earth is given by

and that for the sun

(The angles are very small and hence need not to consider sin? etc.)

(b.) Based on the answers to part (a.), is a total eclipse of the sun really "total"?

No, as the angle subtended by the moon is slightly less then that by the sun, the eclipse will not be total in this situation.

(c.) What is the ratio (as a percentage) of the apparent circular area of the moon to the apparent circular area of the sun?

The apparent (as seen) circular area will depend on the square of the apparent radius of the object which in turn depends on the angle subtended by the object on the eye and hence the circular area will be proportional to the square of the angle subtended on the eye and is given by

or the apparent area of the moon is 93.65% of that of the sun.