Select all the true equations.
A. $\cos (15) = \sin (15)$
B. $\cos (75) = \sin (15)$
C. $\cos (75) = \cos (15)$
D. $\cos (15) = \sin (75)$
E. $\tan (15) = \tan (75)$

Answer

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Answer

\boxed{\text{Final Answer: The true equations are B and D.}}

Steps

Step 1 ：Evaluate each equation using trigonometric functions:

Step 2 ：A. $\cos (15) = \sin (15)$ is False

Step 3 ：B. $\cos (75) = \sin (15)$ is True

Step 4 ：C. $\cos (75) = \cos (15)$ is False

Step 5 ：D. $\cos (15) = \sin (75)$ is True

Step 6 ：E. $\tan (15) = \tan (75)$ is False

Step 7 ：\boxed{\text{Final Answer: The true equations are B and D.}}