Not sure if i've got the trig functions correct

In summary: This is a fundamental identity in trigonometry known as the Pythagorean identity. In summary, the conversation is about the Pythagorean identity in trigonometry and the confusion surrounding the use of trigonometric functions and their reciprocals. The person is seeking help in understanding and remembering the correct formulas.
  • #1
groom03
27
0
I'm doing A2 Edexcel maths and i keep on forgetting the trig functions so can someone take a look and tell me if I've got it right.

So far:

Sin^2(x)=cos^2(x)=1

so:

sin^2(x)=1-cos^2(x)

cos^2(x)=1-sin^2(x)

this is where i get abit stuck

(sin^2(x)+cos^2(x)=1)/cos^2(x) = tan^2(x)+1=sec^2(x)

(sin^2(x)+cos^2(x)=1)/sin^2(x) = tan^2(x)+1=sec^2(x)

i'm not sure if I've got them wrong or if I'm meant to divide by sin(x) or sin^2(x)

Please help me :smile:
 
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  • #2
just looked and i don't think i should have divided by sin^2(x) because the powers on sin/cos would be wrong... i think
 
  • #3
groom03 said:
just looked and i don't think i should have divided by sin^2(x) because the powers on sin/cos would be wrong... i think

[tex]\frac{a^2}{b^2} = (\frac{a}{b})^2, b \neq 0[/tex]
 
  • #4
groom03 said:
(sin^2(x)+cos^2(x)=1)/cos^2(x) = tan^2(x)+1=sec^2(x)

(sin^2(x)+cos^2(x)=1)/sin^2(x) = tan^2(x)+1=sec^2(x)

tan = sin/cos.

1st equation here looks good.
2nd equation: you get a cos/sin term, that is not = tan.
 
  • #5
groom03 said:
I'm doing A2 Edexcel maths and i keep on forgetting the trig functions …

Hi groom03! :smile:

hmm … how to remember trigonometric identities … ? :rolleyes:

I always find that the safest plan is to write down what I think the formula is, and then multiply by cos2 or sin2 to check it.

For example, if I get confused :confused: and think cosec2 + cot2 = 1, then I multiply by sin2 and get 1 + cos2 = sin2 … which it isn't! :wink:
 
  • #6
Redbelly98 said:
tan = sin/cos.

1st equation here looks good.
2nd equation: you get a cos/sin term, that is not = tan.


i keep on getting sin/cos and cos/sin wrong, and i just realized the second equation should equal cosec^2(x).

Thanks for your help
 
  • #7
groom03 said:
I'm doing A2 Edexcel maths and i keep on forgetting the trig functions so can someone take a look and tell me if I've got it right.

So far:

Sin^2(x)=cos^2(x)=1

I am guessing that this is a typo. You surely mean:

[tex] \sin^2(x) + \cos^2(x) =1 [/tex]
 

1. What are the basic trigonometric functions?

The basic trigonometric functions are sine, cosine, tangent, cotangent, secant, and cosecant.

2. How do I know if I've got the trig functions correct?

You can check your answers by using a calculator or by using the unit circle to find the values of the functions at different angles.

3. What is the unit circle and how does it relate to trigonometric functions?

The unit circle is a circle with a radius of 1, centered at the origin of a coordinate plane. It is used to visualize the relationship between the values of the trigonometric functions and the angles in a right triangle.

4. What are the common mistakes when working with trigonometric functions?

Some common mistakes when working with trigonometric functions include forgetting to convert angles from degrees to radians, using the wrong trigonometric function for a given angle, and forgetting to simplify the answer.

5. How can I improve my understanding of trigonometric functions?

Practice is key to improving your understanding of trigonometric functions. You can also review the definitions and properties of the functions, as well as their relationships to each other and to the unit circle.

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