use the formula
R² = P² + Q² + 2 P Q cos Ф
= 30² + 40² + 2 30 40 cos 60
= 900 + 1600 + 2400 * 1/2
= 3700
R = 10 √37 Newtons
angle of the resultant force with 30 N force is
tan α = Q sin Ф / (P + Q cos Ф)
= 40 √3 / 2 (30+40*1/2) = 2√3 / 5
α = inverse tan (2√3/5) = 34.7 degrees
