Physics problems sometimes require you to have some trigonometry under your belt. To see what kind of trig you need, take a look at the figure, which shows a right triangle. The long side is called the hypotenuse, and the angle between x and y is 90 degrees.
Physics problems require you to be able to work with sines, cosines, and tangents. Here’s what they look like for the image:
You can find the length of one side of the triangle if you’re given another side and an angle (not including the right angle). Here’s how to relate the sides:
And here’s one more equation, the Pythagorean theorem. It gives you the length of the hypotenuse when you plug in the other two sides:
Practice questions
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Given the hypotenuse h and the angle theta in the diagram above, what is the length x equal to?
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2.If x = 3 m and y = 4 m in the diagram above, what is the length of h?
Following are the answers to the practice questions:
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x = h cos theta
Your answer comes from the definition of cosine.
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5
Start with the Pythagorean theorem:
Plug in the numbers, and work out the answer:
