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
![\text{Distance 1=speed}* time](https://img.qammunity.org/2023/formulas/mathematics/high-school/pg2o2rbas6qagfp4xs613kqfmjms292033.png)
Substitute speed=20 and time =t, we get
![\text{Distance1=20t}](https://img.qammunity.org/2023/formulas/mathematics/high-school/8pkaib4887uz8o3zuikru05s3j3lsu76e4.png)
After t hours the distance traveled by the second friend is
![\text{Distance 2 =speed}* time](https://img.qammunity.org/2023/formulas/mathematics/high-school/wfqe4lr254un2vhc2bfymi0zkbdohrbf5h.png)
Substitute speed=50 and time =t, we get
![\text{Distance 2 =}50t](https://img.qammunity.org/2023/formulas/mathematics/high-school/sfjmg63iqamgbytttnwsjyb73ynbcecrx8.png)
Using the Pythagoras theorem to find the distance between two friends.
Distance between two friends is
![\text{distance }^2=(20t)^2+(50t)^2](https://img.qammunity.org/2023/formulas/mathematics/high-school/ugiizktbx3ay0xkdldi2mj3gpjhzmrmi05.png)
![\text{distance }^2=20^2t^2+50^2t^2](https://img.qammunity.org/2023/formulas/mathematics/high-school/cto6zyab24qcr51zuibdebugeb6zw3rgee.png)
![\text{distance }^2=400r^2+2500r^2](https://img.qammunity.org/2023/formulas/mathematics/high-school/fq1vd7qdnxrta3beo617lids325j43cf6d.png)
![\text{distance }^2=2900t^2](https://img.qammunity.org/2023/formulas/mathematics/high-school/h41z03cifeczyekyr4pddxhk2ltgym5pz0.png)
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)