2021 AMC 12B Problems/Problem 13: Difference between revisions
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==Solution== | ==Solution== | ||
First, move terms to get <math>1+5cos3x=3sinx</math>. After graphing, we find that there are <math>\boxed{6}</math> solutions (two in each period of <math>5cos3x</math>). -dstanz5 | |||
== Video Solution by OmegaLearn (Using Sine and Cosine Graph) == | |||
https://youtu.be/toBOpc6vS6s | |||
~ pi_is_3.14 | |||
==See Also== | ==See Also== | ||
{{AMC12 box|year=2021|ab=B|num-b=12|num-a=14}} | {{AMC12 box|year=2021|ab=B|num-b=12|num-a=14}} | ||
{{MAA Notice}} | {{MAA Notice}} | ||
Revision as of 21:54, 11 February 2021
Problem
How many values of 
in the interval 
satisfy![\[1-3\sin\theta+5\cos3\theta?\]](http://latex.artofproblemsolving.com/c/2/4/c24b458f389d63f407e3740dc64386119db8a8c3.png)
Solution
First, move terms to get 
. After graphing, we find that there are 
solutions (two in each period of 
). -dstanz5
Video Solution by OmegaLearn (Using Sine and Cosine Graph)
~ pi_is_3.14
See Also
| 2021 AMC 12B (Problems • Answer Key • Resources) | |
| Preceded by Problem 12 |
Followed by Problem 14 |
| 1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 • 11 • 12 • 13 • 14 • 15 • 16 • 17 • 18 • 19 • 20 • 21 • 22 • 23 • 24 • 25 | |
| All AMC 12 Problems and Solutions | |
These problems are copyrighted © by the Mathematical Association of America. 
