Solve Math Trig Identities w/ Sin & Cos Only

In summary, The conversation is about solving an equation using only sine and cosine, rather than tangent. The first step is to replace the values of cosine and sine with their actual values. The conversation also mentions simplifying expressions using trig identities and factoring out sin and cos.
  • #1
Stanc
60
0
Hi I am in need of some help for this question:

1+tanx/1-tanx = tan(x+(∏/4))

It is easy to solve with the tan trig identites on the right side however, my teacher had told me to do it with SIN and COS only. I am not sure if its possible and was looking for some insight

Left Side:
Cosx+Sinx/Cosx-Sinx


Right Side:
End up with
{(SinxCos∏/4) + (CosxSin∏/4)}/ (CosxCos∏/4) - (SinxSin∏/4)

Can anyone give me some insight?
 
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  • #2
A good first step is to replace cos([itex]\pi[/itex]/4) and sin([itex]\pi[/itex]/4) by their actual values.
 
  • #3
pasmith said:
A good first step is to replace cos([itex]\pi[/itex]/4) and sin([itex]\pi[/itex]/4) by their actual values.

Yes. I have tried that but then i get stuck at:

(Sinx(√2/2)) + (Cosx(√2/2)) / (Cosx(√2/2)) - (Sinx(√2/2))

IS there anything i can do?
 
  • #4
Don't get confused by all the notation. This is just the same as simplfying something like
$$\frac{3a + 3b}{3c - 3d}$$
 
  • #5
AlephZero said:
Don't get confused by all the notation. This is just the same as simplfying something like
$$\frac{3a + 3b}{3c - 3d}$$

I don't think I am catching it. I understand how to simplify the example you had but i cannot factor out a sin or a cos?
 
  • #6
Nevermind, I feel reallydumb... i got it, thanks guys
 
  • #7
Stanc said:
Hi I am in need of some help for this question:

1+tanx/1-tanx = tan(x+(∏/4))
The left side needs parentheses!

What you wrote is 1 + (tanx)/1 - tanx, which is equal to 1.

What you meant was (1 + tanx)/(1 - tanx).
 

What are trigonometric identities?

Trigonometric identities are mathematical equations that involve sine and cosine functions and are used to simplify and manipulate trigonometric expressions.

Why is it important to know how to solve math trig identities?

Solving math trig identities is important because it allows for simplification of complex trigonometric expressions, making it easier to solve more advanced mathematical problems.

Can trigonometric identities be proven?

Yes, trigonometric identities can be proven using various mathematical techniques such as algebraic manipulation, substitution, and trigonometric identities themselves.

What is the difference between using sine and cosine in trigonometric identities?

Sine and cosine are both trigonometric functions, but they have different properties and can be used to simplify different types of trigonometric expressions. Sine is usually used for expressions involving angles, while cosine is used for expressions involving lengths.

How can I practice solving math trig identities with only sine and cosine?

You can practice solving math trig identities with only sine and cosine by using practice problems and worksheets that focus on these types of identities, or by creating your own problems and solving them. Online resources and textbooks can also provide helpful examples and exercises to improve your skills.

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