ncert example 1.7 phy class 12 part 1

pg 18

how F3=(3)^1/2 F

F₁=F₂=F
angle between the forces = 60 degrees.
By the addition of vectors,
magnitude of resultant vector is:
$$\begin{gathered} =\sqrt{{F^2}_2+{F^2}_1+2{F^{}}_1{F^{}}_2\cos 60} \\ =\sqrt{3}F \end{gathered}$$