What is the derivative of $f(x)=cos(pi/2-x)$ ?

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Answer 1 · 2017-02-22T00:26:58

$d/dx cos (pi/2-x) = cosx$

Using the trigonometric formula:

$cos(alpha-beta) = cos alpha cos beta + sin alpha sin beta$

we have:

$cos (pi/2-x) = sinx$

so:

$d/dx cos (pi/2-x) = d/dx sinx = cosx$

What is the derivative of f(x)=cos(pi/2-x)f(x)=cos(pi/2-x)?