AM-2704

Double angle formulae

A Math · Secondary 4 · Hard · Double angle formulae

Solve the equation

2\sin2x+\cos x=0

for

0^\circ\le x\le180^\circ

.

$90^\circ$ only
$90^\circ,\ 150^\circ$
$45^\circ,\ 135^\circ$
No solution in this interval

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