Trig. Identities

Question 1

sin²(x)

Answer 1

1 - cos²(x), 1 - cos(2x)/2

Question 2

cos²(x)

Answer 2

1 - sin²(x), 1 + cos(2x)/2

Question 3

tan²(x)

Answer 3

sec²(x) - 1

Question 4

cot²(x)

Answer 4

csc²(x) - 1

Question 5

sin(2x)

Answer 5

2sin(x)cos(x)

Question 6

cos(2x)

Answer 6

cos²(x) - sin²(x)
2cos²(x) -1
1 - 2sin²(x)

Question 7

tan(2x)

Answer 7

2tan(x)/1-tan²(x)

Question 8

sin(x/2)

Answer 8

±√(1-cos(x)/2)

Question 9

cos(x/2)

Answer 9

±√1+cos(x)/2

Question 10

tan(x/2)

Answer 10

√1-cos(x)/1+cos(x)
1-cos(x)/sin(x)
sin(x)/1+cos(x)