Charles B.
asked • 08/07/13(Theta)Cos=1 (Theta)Sin=
I'm having a couple issues with Trigonometry. Some people are telling me I need a calculator but others say I can solve without one, plus I'm not allowed to use one on the test. Is there anyway that you can help me out and explain what to do if I were to receive a problem like the one above or some along the lines of Ex: Cos 65.
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1 Expert Answer
Stuart R. answered • 08/07/13
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THE SHORT ANSWER IS YES.
BUT.... YOU SHOULD LEARN (MEMORIZE) THE DOUBLE ANGLE FORMULAS AND THE 1/2 ANGLE FORMULAS TO EASILY SOLVE YOUR EXAMPLE.
For cosΘ = 1 is just at what angle is the cosΘ = 1 or arccos 1 =Θ
If you remember the unit circle then the cos = x/r which will happen when x = r or when the angle = 0º and 180º and 360º etc.3
For the sine we get y/r or when y = r which is at 90º etc..
Gene G.
Good advice from Stuart! Here's a little more clarification for the particular example of cos(?) and sin(?). The sine and cosine both have the same wave shape, but they are shifted relative to each other. Starting at ?=0 degrees, sin(?) is zero and cos(?) = 1. At 90 degrees, sin(?) reaches 1 and cos(?) has dropped to zero. At 180 degrees, sin(?) has again reached zero and cos(?) hits its minimum at -1, and so on... Sketch them out to see how this looks.
Angle: 0 90 180 270 360
sin( ) 0 1 0 -1 0 ...
cos( ) 1 0 -1 0 1 ...
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08/07/13
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Gene G.
I see that the theta doesn't make it through in comments, although the input box allows you to select it as special character. It came through as question marks!
08/07/13