Question

2sin18cos18cos36/2cos18
помогитеееее​

Answer 1

Объяснение:

$\frac{2*sin18^0*cos18^0*cos36^0}{2*cos18^0} =\frac{sin36^0*cos36^0}{2*cos18^0} =\frac{2*sin36^0*cos36^0}{2*2*cos18^0} =\frac{sin72^0}{4*cos18^0}=\\ =\frac{sin(90^0-18^0)}{4*cos18^0} =\frac{cos18^0}{4*cos18^0} =\frac{1}{4}=0,25.$