trig fursonas

Question 1

cos(2x)

Answer 1

1 - 2sin^2(x)
or
2cos^2(x) - 1
(de moivre real part)

Question 2

sin(2x)

Answer 2

2sin(x)cos(x)
(de moivre imaginary part)

Question 3

sin^2(x)

Answer 3

1/2 (1 - cos(2x))
(de moivre real part reversed)

Question 4

sin^2(x) + cos^2(x)

Answer 4

1
(pythagoras)

Question 5

1 + tan^2(x)

Answer 5

sec^2(x)
(from sin^2 + cos^2)

Question 6

sec^2(x) - 1

Answer 6

tan^2(x)
(from sin^2 + cos^2)

Question 7

1 as trig functions

Answer 7

sin^2(x) + cos^2(x)
or
sec^2(x) - tan^2(x)