- #1
k31453
- 58
- 0
How?? Which Trig Identityis that?
sin^2 = 1- cos^2 ??
Homework Statement
Homework Equations
The Attempt at a Solution
sin^2 = 1- cos^2 ??
Last edited by a moderator:
ehild said:Yes. one of the relevant equation is sin2θ=1-cos2θ.
The other one is cos(2θ)=cos2θ-sin2θ. From these, you get the identity
sin2θ=.5(1-cos(2θ)). Use it.
ehild
k31453 said:but there is no sin..
ehild said:The equation you wrote in the first post is wrong. Correctly, it should be:
2000sin2(500πt)=1000(1-cos(1000πt)).
ehild
The best way to know which trig identity to use is to familiarize yourself with the most commonly used identities and practice applying them to different problems. It also helps to understand the relationship between the different trigonometric functions and how they can be manipulated to simplify expressions.
The trig identity you use will depend on the specific problem you are trying to solve. It is important to carefully analyze the given information and determine which trig identity is most appropriate for the situation.
Memorizing all the trig identities can be challenging, but it can be helpful to break them down into smaller groups and practice them regularly. It can also be useful to understand the derivations of the identities, as this can help with remembering them.
The most commonly used trig identity for finding angles is the inverse trigonometric functions, such as sin^-1, cos^-1, and tan^-1. These functions allow you to find the angle measure given the ratio of sides in a right triangle.
To prove a trig identity, you must show that one side of the equation can be manipulated to be equal to the other side. This can be done by using algebraic manipulations, known trig identities, or other mathematical techniques.