Trig Function Help: Get Answers Now

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    Function Trig
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SUMMARY

The discussion focuses on solving the trigonometric equation involving the double angle formula for cosine, specifically cos(2t). Participants clarify that the problem requires using cotangent values to derive sine and cosine values through the relationships cot = 1/tan and cot = cos/sin. The formula for cos(2t) is confirmed as cos²(t) - sin²(t). A reference triangle is utilized to find the necessary values, leading to the conclusion that the answer is 9/41.

PREREQUISITES
  • Understanding of trigonometric identities, specifically the double angle formulas.
  • Familiarity with cotangent, tangent, sine, and cosine relationships.
  • Ability to construct and analyze reference triangles in trigonometry.
  • Basic algebra skills for manipulating trigonometric equations.
NEXT STEPS
  • Study the derivation and applications of the double angle formulas in trigonometry.
  • Learn how to convert between cotangent and tangent values effectively.
  • Practice constructing reference triangles for various trigonometric functions.
  • Explore additional resources on solving trigonometric equations without calculators.
USEFUL FOR

Students studying trigonometry, educators teaching trigonometric identities, and anyone preparing for tests involving trigonometric equations and functions.

Eric Manuel
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thanks
 
Last edited:
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Can you give the entire problem?
 
Jimmy Johnson said:
Can you give the entire problem?

all that's given is that
 
What is the question? What are you asked to find?
 
MostlyHarmless said:
What is the question? What are you asked to find?
what is =cos2x
 
What is x supposed to be? Is the given problem in terms of t? Are you trying to solve for t and then plug that value in for x?
 
oh my bad its cos2t

its basically asking you to use the double angle formula
but I am not sure how to find those values
 
If you're simply trying to find t, then use cot = 1/tan... If you have a value for t why do you need to use the double angle identities?
 
to find what cos2t is ...

you can find what tan is from cot
then i drew a triangle and got the hypot to be sqrt(41)

but how do i do that math

formula for cos2t = cos^2(t) - sin^2(t)
 
  • #10
Are you forbidden from using a calculator?
 
  • #11
Jimmy Johnson said:
Are you forbidden from using a calculator?

teacher said u can use it
but need to know how to do it without one for test
 
  • #12
Well that may have been useful information at the start...

you have cot = -5/4, find what tan is then recall tan = sin/cos ... or recall cot = cos/sin...
 
  • #13
well i worked it out and i believe i got the answer to be 9/41
 
  • #14
That's what I'm getting
 

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