Question

If tan A - tan B=x and cot B - cotA=y, then
cot (A-B) = .........
(A) 1/y-1/x
(B) 1/x-1/y
(C) 1/x+1/y
(D) xy/x-y​

Answer 1

---------------------------------------------

The direction of magnetic field at the centre

of the circular loop depends on whether the

current in the loop flows in clockwise or

anticlockwise direction.When the current is in

clockwise direction, the magnetic field goes

into the side of wall.

when current is in clockwise direction the

direction of magnetic field (B) is towards

the circuit on the other hand when current

is in anticlockwise direction the direction of

magnetic field (B) is outwards the circuit.

Answer 2

Answer:

This implies that

x2+2ax=4x−4a−13

or

x2+2ax−4x+4a+13=0

or

x2+(2a−4)x+(4a+13)=0

Since the equation has just one solution instead of the usual two distinct solutions, then the two solutions must be same i.e. discriminant = 0.

Hence we get that

(2a−4)2=4⋅1⋅(4a+13)

or

4a2−16a+16=16a+52

or

4a2−32a−36=0

or

a2−8a−9=0

or

(a−9)(a+1)=0

So the values of a are −1 and 9.