Two forces have the sum of their magnitude 18N and the resultant is sqrt 228 when theyre at 120 degrees .
Calculate the two forces
@abhisar

Question

Two forces have the sum of their magnitude 18N and the resultant is sqrt 228 when theyre at 120 degrees .
Calculate the two forces
@abhisar

l · Answer

Let $x$ and $18- x$ be the two forces. By vector law of addition, we know that$$\sqrt{228} = \sqrt{x^2 + (18-x)^2 + 2x(18-x)\cos(120^{\circ})}$$

aaronandyson · Answer

whats the value of cos 120? 1?

l · Answer

You should know your trigonometry for that. 
It is $-1/2$.

aaronandyson · Answer

so thats 
x^2 + 324+x^2-36x +36x - 2x^2 *-1/2

aaronandyson · Answer

it is 16N,2N?

mjdennis · Answer

For what it's worth, you can type "cos(120 deg)" into Google.  It will make you look a lot more responsible, like a good citizen of OS, if you don't have to ask for help in the basics.

michele_laino · Answer

hint:
starting from the formula of @L , after a simplification, we get the subsequent quadratic equation:
$$3{x^2} - 54x + 96 = 0$$
please solve for $x$

aaronandyson · Answer

so thats 16 and 2
i posted it above

michele_laino · Answer

yes! That's right!