Finally, we convert the angle from degrees to radians.There are other ways to solve this problem. For example, you could first find ș using the arccosine function, and then use the tangent ratio to
find the length of the third side.Step Reason
10.ș = (61.7°)(2ʌ rad/360°) multiply by conversion factor
11.ș = 1.08 rad multiplication and division
1.15 - Interactive checkpoint: trigonometry
The great pyramid of Cheops has a
square base with edges that are
almost exactly 230 m long. The side
faces of the pyramid make an angle
of 51.8° with the ground.
The apex of the pyramid is directly
above the center of the base. Find its
height.
Answer:h = m
1.16 - Gotchas
The goal of “gotchas” is to help you avoid common errors. (Not that your teacher’s tests would ever try to make you commit any of these
errors!)
Confusing weight and mass. You do not weigh 70 kilograms, or 80, or 60. However, those values could very well be your mass, which is an
unchanging value that reflects your resistance to a change in motion.
Converting units with factors incorrectly oriented. There could probably be an essay written on this topic. Make sure the units cancel! is
probably the best advice we can give. For example, if you are converting meters per second to miles per hour, begin by multiplying by a
conversion fraction of 3600 seconds over one hour. This will cause the seconds to cancel and hours to be in the right place. (If this is not clear,
write it down and strike out units. If it is still unclear, do some practice problems.) In any physics calculation, checking that the units on each
side are consistent is a good technique.(^18) Copyright 2000-2007 Kinetic Books Co. Chapter 01