Solving (-1)vcos θ Identity Problem - Hi Friends!

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In summary, the identity (-1) power v cosθ is derived from the pattern seen when calculating sin and cos values for v=...-2,-1,0,1,2... By omitting the sine term, we can write the identity as (-1) power v cosθ. This helps to understand the basic problem.
  • #1
nesta
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Hi friends,

I am not able to understand how the below shown identity becomes (-1) power v cosθ.

cos(vπ − θ ) = cos vπ cos θ + sin vπ sin θ = (−1)power v cos θ


==> (-1)vcos θ

Please help me understand this basic problem.

Thanks,
Nesta
 
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  • #2
You must mean v is an integer. So v=...-2,-1,0,1,2... Start working out sin(1*pi), sin(2*pi), sin(3*pi) ... and cos(1*pi), cos(2*pi), cos(3*pi) ... Do you see a pattern?
 
  • #3
Dick said:
You must mean v is an integer. So v=...-2,-1,0,1,2... Start working out sin(1*pi), sin(2*pi), sin(3*pi) ... and cos(1*pi), cos(2*pi), cos(3*pi) ... Do you see a pattern?
Thank you very much, I understand now.

cos vπ cos θ + sin vπ sin θ

Since sin n*pi is always zero, we can omit this.

when,
v=0 : cos(0π)cosθ + sin0 = cosθ
v=1 : cos(1π)cosθ + 0 = -1 cosθ
v=2 : cos(2π)cosθ + 0 = 1 cosθ
v=3 : cos(3π)cosθ + 0 = -1 cosθ

so in general we can write it as (-1)to power v cos θ

Thank you very much.
 

What is (-1)vcos θ identity problem?

The (-1)vcos θ identity problem is a mathematical equation that involves solving for the value of a variable, v, in a trigonometric expression involving cosine, θ, and a negative coefficient.

How do I solve (-1)vcos θ identity problem?

To solve this problem, you will need to use trigonometric identities, specifically the Pythagorean identity (cos²θ + sin²θ = 1) and the double angle identity (cos 2θ = 2cos²θ - 1). You will also need to use algebraic manipulation to isolate the variable v on one side of the equation.

What are some tips for solving (-1)vcos θ identity problem?

One tip is to start by simplifying the equation using the Pythagorean identity, and then substituting in the double angle identity for cos 2θ to get rid of the θ term. Another tip is to carefully keep track of your steps and make sure you are consistently solving for the same variable.

Why is solving (-1)vcos θ identity problem important?

Solving this type of problem is important because it allows you to manipulate and simplify trigonometric expressions, which are commonly used in physics, engineering, and other scientific fields. It also helps develop critical thinking and problem-solving skills.

Can you provide an example of solving (-1)vcos θ identity problem?

Yes, for example, if the equation is (-1)vcos θ = 4, you can use the Pythagorean identity to get rid of the cos θ term and solve for v, giving you v = 4/-1 = -4. You can then check your answer by substituting it back into the original equation and seeing if it satisfies the equation.

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