Anyone can show me the method?

1. In a triangle PQR, PQ=a, QR=a+d, RP=a+2d and

, where a and d are positive constant, show that

2. A man observed the top of a tower from the points A, B and C along a straight, horizontal road, where AB=a and BC=b. The angle of elevation of the top of the tower from A is

while the angle of elevation from B and C are both equal to

. If

is the angle of elevation of the top of the tower from the point E wich is the mid-point of BC, show that

i)

is the largest angle of elevation,

ii)