The MCB of a rupas room is tripped and keeps on tripping again and again, and if it is a domestic circuit, what could be the reason for this phenomenon?
The reason could be a short circuit which is resulting in higher level of currents to pass through the MCB which is resulting in trip every time.
OR
The MCB is faulty and might need a replacement.
To Diagnose the problem further more.
Turn off all the switches in rupas room and then try turning on the MCB. If it trips again then MCB is faulty (Subjective to the fact there everything was normal before this issue and no signs of short circuit or spark in wiring were observed)
If MCB does not trip in point 1 then Turn ON all the switches one by one. This shall give you the cause of problem.
Answer:
The answer is β=0,85 rads
Explanation:
As the ladder is leaning against the building, we can imagine there´s a triangle where 20ft is the hypotenuse and 15ft is the maximum vertical distance between the ladder and the ground, it means, the leg opposite to β which is the angle we need
Let β(betha) be the angle between the ladder and the ground
We also know that 
In this case we will need to find β, this way:

Then β=48,6°
We also have that 2πrads is equal to 360°, in this way we find how much β is in radians:

then we find β=0,85rads
Answer:
A. F=107.6nN
B. Repulsive
Explanation:
According to coulombs law, the force between two charges is express as
F=(Kq1q2) /r^2
If the charges are of similar charge the force will be repulsive and if they are dislike charges, force will be attractive.
Note the constant K has a value 9*10^9
Hence for a charge q1=7.10nC=7.10*10^-9, q2=4.42*10^-9 and the distance r=1.62m
If we substitute values we have
F=[(9×10^9) ×(7.10×10^-9) ×(4.42×10^-9)] /(1.62^2)
F=(282.4×10^-9)/2.6244
F=107.6×10^-9N
F=107.6nN
B. Since the charges are both positive, the force is repulsive
I think is A or B it depends on like what the trying to answer