Calculate the resultant of four forces 12N, 10N, 15N, 9N with 40 degrees, 30 degrees, 60 degrees.

I DO NOT KNOW !

assuming the 1st force is at 0°, just add up the x- and y-components of the 4 forces, where as usual,

x = F cosθ
y = F sinθ
for each force
post your work if you get stuck

say the 12 N is in x direction

then x component of all = Fx = 12 + 10 cos 40 + 15 cos 30 + 9 cos 60
and y component of all = Fy = 0 + 10 sin 40 + 15 sin 30 + 9 sin 60
|F| = sqrt (Fx^2 + Fy^2)
tan angle above x axis = Fy/Fx

To calculate the resultant of multiple forces, we need to find the vector sum of all the forces. We will do this by splitting each force into its horizontal and vertical components. Then, we will add all the horizontal components together and all the vertical components together. Finally, we will find the magnitude and direction of the resultant vector using the Pythagorean theorem and inverse trigonometric functions.

First, let's find the horizontal and vertical components of each force using trigonometry. We'll assume that the positive x-axis is horizontally to the right, and the positive y-axis is vertically upwards.

Force 1 (12N):
Horizontal component: 12N * cos(40 degrees)
Vertical component: 12N * sin(40 degrees)

Force 2 (10N):
Horizontal component: 10N * cos(30 degrees)
Vertical component: 10N * sin(30 degrees)

Force 3 (15N):
Horizontal component: 15N * cos(60 degrees)
Vertical component: 15N * sin(60 degrees)

Force 4 (9N):
Horizontal component: 9N * cos(0 degrees) (since 0 degrees is along the x-axis)
Vertical component: 9N * sin(0 degrees) (since 0 degrees is along the x-axis)

Now, let's add up all the horizontal and vertical components separately:

Horizontal component of the resultant = Sum of all horizontal components
= (12N * cos(40 degrees)) + (10N * cos(30 degrees)) + (15N * cos(60 degrees)) + (9N * cos(0 degrees))

Vertical component of the resultant = Sum of all vertical components
= (12N * sin(40 degrees)) + (10N * sin(30 degrees)) + (15N * sin(60 degrees)) + (9N * sin(0 degrees))

Next, we can find the magnitude and direction of the resultant vector using the Pythagorean theorem and inverse trigonometric functions:

Magnitude of the resultant vector = sqrt((Horizontal component of the resultant)^2 + (Vertical component of the resultant)^2)

Direction of the resultant vector = arctan((Vertical component of the resultant) / (Horizontal component of the resultant))

Finally, substitute the values in the formulas and perform the calculations to find the magnitude and direction of the resultant vector.