Hi!!!

Hope you are doing well.

The resultant of these two forces is given as

F1=F2=10 dynes.

Angle between F1&F2 = (180-60) = 120.

Resultant F:

Mod(F) = square root(F1^2+F2^2+2F1F2cos 120)

= square root(10^2+10^2+2(10)(10)(-0.5))

= 10

Therefore, the resultant force has also the magnitude of 10 dynes.

Hope you are clear now. Feel free to ask if you have any other queries. All The Best!!!