Answer:
option 2
Explanation:
The problem can be solved using Pythagoras' identity for a right triangle.
The angle between due East and due North is 90°
The solution here involves using the Cosine rule.
let x be the direct distance between house and office, then
x² = 17² + 21² - 2(17)(21)cos90° → option 2
Note that since cos90° = 0 the equation reduces to
x² = 17² + 21² ← Pythagoras' identity