Given:
One friend heads north 20 miles per hour.
Other heads East 50 miles per hour.
let r be the number of hours traveled.
After t hours the distance traveled by the first friend is

Substitute speed=20 and time =t, we get

After t hours the distance traveled by the second friend is

Substitute speed=50 and time =t, we get

Using the Pythagoras theorem to find the distance between two friends.
Distance between two friends is




Taking square root on both sides, we get
![\text{distance }=\sqrt[]{2900t^2}](https://img.qammunity.org/2023/formulas/mathematics/high-school/db6ib3wptutvdiem83yhmcsr7x6j9yxbv6.png)
![\text{distance }=10\sqrt[]{29}t](https://img.qammunity.org/2023/formulas/mathematics/high-school/icyotj5m6xx2ire1cgn7vm9m1cvvms8r6d.png)
Hence the required distance is
![\text{distance }=10\sqrt[]{29}.t](https://img.qammunity.org/2023/formulas/mathematics/high-school/of5of6ddncmwvvdzr20mtjrzxuaiasim2i.png)