A straight wall h meters high stretches in the direction of 0 (angle 0 is counted from south to west). Prove that on the days of the equinox the wall does not cast a shadow, when the hour angle of the Sun t is determined by the formula tg t = sin ф tan 9, and show that at true noon the width of the shadow is h tg ф sin 9.
1) It is required that the azimuth of the Sun is equal to 0. From formulas (5), (6) of Section III, setting b = 0 and A = 0, we find the required formula 2) x = h tan z X cos (90 -0), but z = f – b = f – 0 = f, therefore, x = h tg f sin 0.
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