True or false: identities and parity

Exercise and reference answers

Questions

1. Statement is true

   Yes

   Statement

   cos²x + sin²x = 1 for every x.

2. Statement is true

   Yes

   Statement

   sin(−x) = −sin x.

3. Statement is true

   No

   Statement

   cos(−x) = −cos x.

4. Statement is true

   Yes

   Statement

   1 + tan²x = sec²x.

5. Statement is true

   No

   Statement

   1 + tan²x = cosec²x.

Explanation