Ii `DeltaPQR`, PD`bot`QR such that D lies on QR, if PQ=a,PR=b,QD=c and DR=d, then prove that (a+b)(a-b)=(c+d)(c-d).

Explanation

To prove that \((a+b)(a-b)=(c+d)(c-d)\) for triangle \(PQR\) with the given conditions, we can follow these steps:

### Step 1: Identify the triangle and the segments
We have triangle \(PQR\) with \(PD\) perpendicular to \(QR\). Let:
- \(PQ = a\)
- \(PR = b\)
- \(QD = c\)
- \(DR = d\)
...