Question

The figure shows two vectors d₁, and d₂.

If θ = 45°, the magnitude of d₁ is 5.0, and the magnitude of d₂ is 4.0 then what is the magnitude of the vector R where:

Give your answer to 2 s.f.

Answer 1

$|d_1-d_2|=\sqrt{|d_1|^2+|d^2|-2d_1d_2cos\theta}$

$|d_1-d_2|=\sqrt{5^2+4^2-2\cdot4\cdot5/\sqrt{2}}=3.57$