AM-2563

R-formula

A Math · Secondary 4 · Hard · R-formula

Given that

BD = 4\sin\theta + 7\cos\theta

, express

BD

in the form

R\cos(\theta - \alpha)

, where

R>0

and

\alpha

is an acute angle in degrees.

$\sqrt{65}\cos(\theta-29.7^\circ)$
$\sqrt{65}\cos(\theta+29.7^\circ)$
$\sqrt{65}\sin(\theta-29.7^\circ)$
$\sqrt{65}\sin(\theta+29.7^\circ)$

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