How much NaNo3 dissolved in 300 ML at 90 C

ill do it for 100, also this isnt 80 its 40

no. dot product   =0 when vecs at right angles

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west