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# Pythagorean Identities

SATSTM-2QL4BX

Which one of the following is equivalent to $(1-\text{cos x})(1+\text{cos x})$ ?

A

$\cos^{2}x$

B

$\sin^{2}x$

C

$\tan^{2}x$

D

$\cos^{2}x+1$

E

$\sec^{2}x$