4. Three forces act on the jib of a crane, with units of newton's and are given by: 27 (101 _ With the following show how, you obtain the unit vector before finding vectors F> and F; F? has magnitude of 18 and acts in the direction of (5,-7, \\V7) _ F has magnitude of 10 and acts in the direction of (0,-3,4) (a) Find the resultant force that acts on the jib? (b) What additional force must be imposed on the jib to reduce the resultant to zero and so be electronically applied to the braking system on the crane to mcmwoba Eo load acting on it to be still, in mid-air