Since it makes a 15o angle with the vertical, it makes a 75o angle with the
horizontal.
Yes, you can use the Pythagorean theorem. I made a mistake somewhere, but
don't have time to find it and correct it. Maybe you can find the mistake.
horizontal | vertical
components | components
---------------------------------
|P|cos(75o) N ||P|sin(75o) N
100 N | 0 N
---------------------------------
|P|(cos(75o)+100 N | |P|sin(75o) N
______________________________________________________________
|Resultant| = √(sum of horizontal components)2 +(sum of vertical components)2
Square both sides
Subtract 10000 from both sides.
Since
Use the quadratic formula:
We use the + since the - gives a negative value.
That's the magnitude of the force P.
The angle it makes with the x-axis is found by
Edwin