Trig Identities

Question 1

Compound angle

Answer 1

Sin is sin cos and signs normal
Cos is coscos - sin sin
- becomes cos cos + sin sin

Tan divide through, becomes tan x + tan y/ 1 + tan x tan y or -

Question 2

How to rewrite stuff like cos 75 as a Süd-

Answer 2

Pick two angles that can be written as surfs (0 30 45 60 90)

Rewrite and expand

Question 3

Pick wisely for double angle for cos, when dhoudl you choose what

Answer 3

If sqaures involved tan probably first

Otherwise based on like terms pick second third to quadratic it

Question 4

BIG MISTAKE

NEVER DIVIDE BY A TRIG WHEN SO,VING THESE ANGLE QUESTIONS

WHY NOT

Answer 4

ALWAYS FAVTORISE, THIS GETS RID OF A POTENTIAL SOLUTION BECAUSE ITS POSIBLE THST IT COULD BE =
NEVER DO THIS UNLESS COS

Question 5

How to use R formula?

To find r and x

Answer 5

Expand to rn formula they give you to give you compound

Equate coefficients

Now if you swaure both and them together you get a triangle to find value for r

And if you divide one by the other, you get tan x = b/a so you can find out x

And for other a2 +b2 = r2

Question 6

What can you use r formula to do?

How to solve a com0x formula

Answer 6

Can make it one thing so sketching graoh becomes more easier

Can make it into one thing so thst SOLVING A FORMULA BECOMES MUCH EASIER

Question 7

How to know which compound formula to use

Answer 7

EACH SHOULD WORK, procided you do Esch correctly

The only thing is if you observe, try to match one to one that looks like it with the CORRECT SIGNS, will make it easier

For example if cosx + sin y, use cos (x-y) as this matches the order of cos and also THE SIGN IN THE MIDDLE

Question 8

How to even solve these trig things again cuz you clearly forgot

Answer 8

Adjust the range by adding or subtracting whatever happening to x to both 0 and the extreme!

Now solve for it using those new ranges (using cast etc)

Finally adjust