Trigonometric identites

[Hielly]

Hey
See attachment

Thanks

[TrueTears]

If , then because it is a Pythagorean triple, [notice the negative]

[again notice the negative]



Subbing this in yields:

[Hielly]

How do you know about Pythagorean triple ? the exercise says nothing about that :S. i just did a quick search on that term, and realised i have never encountered it :O.

For this question why would the exercise have this sort of question when they dont mention anything about the pythagorean triplet.. or is there another way to solve this.

[TrueTears]

Pythagorean triple is just a fancy name for your 3,4,5 right angle triangle or your 7, 14, 15 right angle triangle etc.

Or you can simply draw a right angle triangle and use Pythagoras' theorem to work out the hypotenuse.

[dcc]

because it is a Pythagorean triple

Is misleading.  Draw a picture, consider quadrants.

[TrueTears]

because it is a Pythagorean triple

Is misleading.  Draw a picture, consider quadrants.

That's what I did.

[olly_s15]

You don't need to know about the Pythagorean triple (although it helps).
You can find cot(x) because it is the reciprocal of tangent, meaning that it would be 3/4.
Because you are given tan(x), you can use the identity of 1 + tan^2(x) = sec^2(x) to then find the value of cos since it is the reciprocal of sec. Then simply use the Pythagorean identity to find sin, then sub it all in as shown in truetears' post. Sorry i don't know how to use latex... but this should be a more familiar way of going about it. And make sure you consider quadrants.