F1 . . . 100% of it = 900N is in the +x direction.
F2 . . . 70.7% of it (cos45°, 530.3N) is in the +x direction, and 70.7% of it (sin45°, 530.3N) is in the +y direction.
F3 . . . 80% of it (520N) is in the -x direction, and 60% of it (390N) is in the +y direction.
Total x-component: 900 + 530.3 - 520 = 1,950.3 N
Total y-component: 530.3 + 390 = 920.3 N
Magnitude of the resultant = √ (x² + y²)
= √(1950.3² + 920.3²)
= √4,650,070.09
= 2,156.4 N .
Angle of the resultant, measured counterclockwise from the +x axis, is
tan⁻¹ (y / x)
= tan⁻¹ (920.3 / 1950.3)
= tan⁻¹ (0.4719)
= about 25.3° .
Caution: The same fatigue that degrades my ability to READ the question accurately may also compromise the accuracy of my solutions. Before you use this answer for anything, check it, check it, check it !
