Answer:

Step-by-step explanation:
Brain correctly use a method of completing the square to solve the equation:

His First Step is to: Take the Constant Term to the Right Hand Side

The Next Step Would be to:
- Divide the Coefficient of x by 2
- Square It
- Add it to both Sides
In this case, the Coefficient of x = 7
- Divided by 2 =

- Squaring It, we have:

It is this number
that is added to both sides in the manner below:

Answer:
Pendulum will swing by an angle 0.666π
Step-by-step explanation:
We have given arc = 
And length of the pendulum l = 150 cm
Length of the pendulum will be equal to radius of the pendulum so r = 150 cm
Arc is given by 
So 

So pendulum will swing by an angle 0.666π