Question

find out angle between 4and 5 unit vector if resultant is 8 vector?​

Answer 1

Answer:

Explanation:  First of all 4 and 5 are not unit vectors as their magnitude is not 1.

8 = $\sqrt{4^{2} + 5^{2} + 2. 4 .5 cos\alpha }$

64 = 16 + 25 + 40 cosα

64 = 41 + 40 cosα

23 = 40 cosα

α= cos⁻¹(23/40)