Question

A student takes his 2 dogs for a walk. He lets them off their leash in a field where Edison runs at 10 m/s and Einstein runs at 8 m/s. The student determines the angle between the dogs is 25°, how far are the dogs from each other in 5 seconds?

Answer 1

The dogs are 21. 8 m from each other in 5 seconds

Explanation:

Given;

speed of Edison, v = 10 m/s

speed of Einstein, u = 8 m/s

angle between the two dogs, θ = 25°

let the distance ran by Edison in 5 seconds = x = (10 m/s x 5 s) = 50 m

let the distance ran by Einstein in 5 seconds = y = (8 m/s x 5 s) = 40 m

let the distance between the two dogs after 5 seconds = z

x , y and z forms a triangle with an angle between x and y as θ

The third side, z, can be calculated using cosine rule

z² = x² + y² - 2xyCosθ

z² = 50² + 40² - (2 x 50 x 40)Cos25

z² = 4100 - 4000Cos25

z² = 474.7689

z = √474.7689

z = 21.789 m ≅ 21. 8 m

Therefore, the dogs are 21. 8 m from each other in 5 seconds