COS (tan i tan 0) The formula D = 24 can be used to approximate the number of hours of daylight when the T declination of the Sun is i at a location 0 north latitude. To use the formula, cos (tan i tan 0) must be expressed in radians. Approximate the number of hours of daylight in a city at 3145 north latitude on (a) the summer solstice (i=23.5), (b) the vernal equinox (i = 0), and (c) July 4 (i=2248'). .. (a) The number of hours of daylight on the summer solstice is 14.08 hours. (Do not round until the final answer. Then round to the nearest hundredth as needed.) (b) The number of hours of daylight on the vernal equinox is 12 hours. (Do not round until the final answer. Then round to the nearest hundredth as needed.) (c) The number of hours of daylight on July 4th is 14.01 hours. (Do not round until the final answer. Then round to the nearest hundredth as needed.)