Is speed the rate of change in the velocity of a moving body?

No, speed is the rate of change of distance.

Velocity is the rate of change of displacement.

Distance is scalar quantity, it has just magnitude.

Displacement is vector quantity, it has both magnitude as well as direction. So, speed and velocity are scalar and vector respectively too.

hope it you

step-by-step explanation:

sin(7pi/6 - pi/3)  

= sin(7pi/6 - 2pi/6)  

= sin(5pi/6)  

= sin(pi - pi/6)  

= sin(pi/6)  

= 1/2  

sin 7pi/6 - sin pi/3  

= sin (pi + pi/6) - sin pi/3  

= -sin pi/6 - sin pi/3  

= -1/2 - sqrt(3)/2  

= -(1+sqrt(3))2