Assertion: trigonometric function's value | /r/CapableOf | satisfy simple identities
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Source sentences:
text: The values of the trigonometric functions of these angles θ , θ ′ {\displaystyle \theta ,\;\theta '} for specific angles α {\displaystyle \alpha } satisfy simple identities: either they are equal, or have opposite signs, or employ the complementary trigonometric function.