1)each of 2 forces has magnitude X N and the resultant of 2 forces has magnitude 12N.when magnitude of 1 force increases by 70%,the magnitude of 2 forces becomes 21N.find X and angle between 2 forces.

2)a force F of magnitude 12N has components P and Q.The sum of magnitude of P and Q is 18N.the direction of Q is at right angle to F.Find magnitude of Q.

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a force F of magnitude 12N has components P and Q.The sum of magnitude of P and Q is 18N.the direction of Q is at right angle to F.Find magnitude of Q.
|P|+|Q|=18                        (1)
sqrt(|P|^2+|Q|^2)=12         (2)
from (1) |P|^2+2|P||Q|+|Q|^2 =324
from (2) (|P|^2+|Q|^2=144 

the difference between these 2 is 2|P||Q|=190 so |P||Q|=90 so |P|=90/|Q| sub into (1)
90/|Q|+|Q|=18
90+|Q|^2=18|Q|
|Q|^2-18|Q|+90=0
This equation has no solutions. Can you check the question?

It is an unlikely event that astar is wrong.