how do i do the following?

Question

find the resultant of the following perpendicular forces: (a) 400N, 0degrees; (b) 820 N, 270degrees; (c) 500 N, 90degrees

COnvert: 6x10^4 mi/hr^2 to m/s^2

and 50m^3/s to ft^3/min

Thank you want to see if my asnwers are accurate

Answer 1

well for the first, intuitively b and c are opposing, with a net result of 320N@270.
remaining two components are 400N@0 =320N@270. simple right triangle mag =sqroot of 320^2+400^2=512.25N
dir = arctan -320/400 = -38.66deg

the others are simple unit conversions you can check on any online converter