Prove that `asqrtb+csqrtb=(a+c)sqrtb`

Prove that 15c_2=105

If a,b,c are in AP, show that 1/((sqrtb+sqrtc)),1/((sqrtc+sqrta)),1/((sqrta+sqrtb)) are in AP.

If A,B,C are the angles of a triangle and tan A=1,tan B=2, prove that tan C=3 If a,b,c are the corresponding sides,then prove that (a)/(sqrt(5))=(b)/(2sqrt(2))=(c)/(3)

(a + b)(sqrta + sqrtb ) (sqrta - sqrtb)= "________"

(sqrta + sqrtb)^2 = ?

In DeltaABC , prove that: acosA+bcosB=(c)cos(A-B)

Prove that A sub B,B sub C and C sub A=>A=C

Prove that the points (a, b + c), (b, c + a) and (c, a + b) are collinear.