What is the approximate magnitude of vector F?

Question

Vectors  and  are shown in the coordinate plane.

Vector  is given by  =  + 

What is the approximate magnitude of vector ?

	8.0
	13
	10
	16
	19

Answer 1

I assume that the angle between the two Vectors B and C is 79

So

F² = B² + C² + 2*B*C Cos 79

⁼ (5.6)² +( 4 .8)² + 2*5.6 *4.8* Cos 79 = 31.36 + 23.4 + 53.76 * 0.19 As Cos 79 =0.19

= 31.36 +23.4 + 10.21 = 64.97

F = √ 64.97 = 8.06

Now you mark the correct choice

(Try to get angle between B and C as 79 )