Betty observed that the lamp post in front of her house casts a shadow of length 8 feet when the angle of inclination of the sun is 60 degrees. How tall is the lamp post? (In a 30-60-90 right triangle, the side opposite 30 is one-half the length of the hypotenuse.)
2007-05-31 16:19:40 · 4 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
H / 8 = tan60 = sqrt(3)
H = 8*sqrt(3) = 13.9 feet
2007-05-31 16:24:31 · answer #1 · answered by Dr D 7 · 1⤊ 0⤋
Always draw a picture. In the 30/60/90 right triangle, the ratio of the sides opposite to the angles is 1, sqrt(3), and 2 respectively.
2007-05-31 23:27:06 · answer #2 · answered by cattbarf 7 · 0⤊ 0⤋
I have seen a lot of these simple geometric questions tonight, don't they teach basic geometry in school anymore?
The answer lies in using Pythagoras's theorem that states in a right triangle, the square of the hypotenuse (that's the long side) is equal to the sum of the squares of the other 2 sides.
2007-05-31 23:23:41 · answer #3 · answered by Anonymous · 0⤊ 0⤋
13.8 feet
2007-05-31 23:26:25 · answer #4 · answered by daisy 1 · 0⤊ 0⤋