Answer:
16.6
Step-by-step explanation:
We know that
2π/3 radians-------> convert to degrees-----> 2*180/3---> 120°
120°=90°+30°
Part a) Find <span>sin(2π/3)
</span>sin(2π/3)=sin (90°+30°)
we know that
sin (A+B)=sin A*cos B+cos A*sin B
so
sin (90°+30°)=sin 90*cos 30+cos 90*sin 30
sin 90=1
cos 30=√3/2
cos 90=0
sin 30=1/2
sin (90°+30°)=1*√3/2+0*1/2-----> √3/2
the answer part a) is
sin(2π/3)=√3/2
Part b) Find cos (2π/3)
cos (2π/3)=cos (90°+30°)
we know that
cos (A+B)=cos A*cos B-sin A*sin B
so
cos (90°+30°)=cos 90*cos 30-sin 90*sin 30
sin 90=1
cos 30=√3/2
cos 90=0
sin 30=1/2
cos (90°+30°)=0*√3/2-1*1/2----> -1/2
the answer part b) is
cos (2π/3)=-1/2
Subtracting the weight of the smaller brick from the larger gives us the weight difference:
4 3/8 lb - 2 1/3 lb. The two denominators are 8 and 3 respectively, resulting in an LCD of 24. Thus, our problem becomes:
4 9/24 - 2 8/24, which equals 2 1/24 lb. The weight difference is 2 1/24 lb.
62,000 is reasonable (because of rounding)90*690=62,000
