Cos 30- cos 70=2 sin 50. sin 20.

L.H.S=2sin(30+70/2).sin(70-30/2)

=2 sin(100/2).sin(40/2)

=2sin50.sin20

Therefore,L.H.S=R.H.S proved

the answer is y = 11.54

hope this : )

hello,

as we don't know if g(x) is continue,

answer b

f(x)=2x²-8x+1=2(x²-4x+4)+1-8=2(x-2)²-7

vertex is (2,-7) ( a minimum since coefficient of x² is > 0)