Answer:

Explanation:
Represent Tristan's house with T, his grandparent's with G and his parents with P.
Such that:


Required
Find TG
To solve this, we make use of Pythagoras Theorem which is represented as:

Substitute values for GP and TP


Collect Like Terms



--- Approximated
Hence, the distance between Tristan ans his grandparent's house is 2.2 miles