In the given figure, P is 300 km Eastward of O and Q is 400 km North of O. R is exactly in the middle of Q and P. The distance between Q and R is :

Options

A. 1. 250 km
B. 2. `250sqrt2km`
C. 3. 300 km
D. 4. 350 km

Answer

A

Explanation

From the given Fig., it is clear that `DeltaPOQ` is right angled at O.

So, PQ =`sqrt(OP^2+OQ^2)=sqrt((300)^2+(400)^2)`
`=sqrt(90000+160000)=500` km
Since R is the midpoint of PQ
Therefore, `QR=1/2xxPQ=250km`