The formula hours.

North latitude .

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(a) Summer solstice , north latitude .

Substitute and in day function .

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(b) Vernal equinox , north latitude .

Substitute and in day function .

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(c) July 4  , north latitude .

Substitute and in day function .

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(d) It s always 12  of day light because at the equator,.

Since the numerator of hours of day light at a location that is north latitude on the summer solstice is almost [from part(a)], therefore, the number of hours of day light on the winter solstice will be almost zero . That means people at the north latitude will not see any day light on the winter solstice.

(a) On Summer solstice is .

(b) On  Vernal equinox is .

(c) On July 4 is .

(d) People at the north latitude will not see any day light on the winter solstice.