Trig identities

Question 1

sin^2x + cos^2x equals

Answer 1

1

Question 2

sinx/cosx

Answer 2

tan x

Question 3

Cos(A+B) =

Answer 3

CosACosB - SinASinB

Question 4

Cos(A-B) =

Answer 4

CosACosB + SinASinB

Question 5

Sin(A+B) =

Answer 5

SinACosB + CosASinB

Question 6

Sin(A-B) =

Answer 6

SinACosB - CosASinB

Question 7

Sin2A=

Answer 7

2SinACosA

Question 8

Cos2A=

3 answers

Answer 8

Cos^2A - sin^2A
2Cos^2A - 1
1 - 2Sin^2A

Question 9

How to expand Cos4A, Sin 4A

Answer 9

Write as (2A + 2A) and expand using the formula -

Question 10

When solving with squared values of sin or cos remember-

Answer 10

That it can be seen as a quadratic so squares can be removed and brackets will = 0
And that cos^-1(>1)or sin^-1(>1) aren’t real.

Question 11

For questions with hence solve when x has been multiplied how to solve

Answer 11

State answers as previous but rather than previous saying x= state multiplex =
Now divide both sides by multiple for x=
The period will now be different so add 360/multiple to all answers, do this until limit is reached.