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The billion dollar questions!?
Help. My book is stupid. I don’t understand it.
P13. The U.S. Weather Bureau defines a cloud ceiling as the altitude of the lowest clouds that cover more than half the sky. To determine a cloud ceiling, a powerful searchlight projects a circle of light vertically on the bottom of the cloud. An observer sights the circle of light in the crosshairs of a tube called a clinometer. A pendant hanging vertically from the tube and resting on a protractor gives the angle of elevation. Find the cloud ceiling if the searchlight is located 1000 feet from the observer and the angle of elevation is 30.0° as measured with a clinometer at eye-height 6 feet. (Assume three significant digits.)
P14. A video camera is to be mounted on a bank wall so as to have a good view of the head teller. Find the angle of depression that the lens should make with the horizontal.
y of the triangle = 5.93
x of the triangle = 12.02 ft
head teller is point A
Just simple goemetry. Get a blank piece of paper. Draw a cloud. Under the cloud (straight down) draw the searchlight on the ground. shining straight up. Far away, also on the ground, draw a guy looking up at the cloud.
Now – the distance between the guy and the light is 1000 feet. The angle he’s looking up at is 30 degrees from horizontal. Draw a right triangle from the guy’s eye, horizontally to the light, up to the cloud, back to the eye. Write 30 degrees on the angle next to the guy.
Then forget all about the guy and the cloud and just do the math based on the triangle.
Don’t forget to add 6 feet to your answer when it’s finished, so that you’re measuring from the ground and not from the guy’s eye.
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