Which of the following equations would result in destructive interference with the wave y= -2sin(2pi/3 x)?
A.) y= -2sin(2pi/3 x)
B.) y=2sin(2pi/3 x)
C.) y= -2sin 3pi/2 x)
D.) y=2sin (3pi/2 x)

I’m stuck on this i don’t understand.

Weak battery is considered to be a part of routine a. inspection b. wear and tear c. maintenance d. check

Grace is standing 18 feet from a lighthouse and kelly is standing 10 feet from grace. the angle that grace looks up to see the top of the lighthouse is 45°. the angle that kelly looks up to see the top of the lighthouse is y°. find the height, h, of the lighthouse. find the angle, rounded to the nearest tenth of a degree, in which kelly looks up to the top of the lighthouse. to the nearest tenth of a degree, find the value of x° . in two or more sentences, explain your calculations