All of the following are pythagorean identities except: a. sec^2(x) + 1 = tan^2(x) b. 1 + cot^2(x) = csc^2(x) c. sin^2(x) + cos^2(x) = 1 d. tan^2(x) + 1 = sec^2(x)

Only A is not Pythagorean Identity.

Step-by-step explanation:

Let us draw a unit circle as shown in the attached figure.

In the given figure, let us apply Pythagorean theorem, which is given by

Divide both sides by

Divide both side of identity C by  

Therefore, only A is not Pythagorean Identity.

a

step-by-step explanation: