1) in order to solve this problem you must to obtain The value of K, for it you know by definition that the horizontal slope of the side BC is zero ,
then m = Y2-Y/X2-X1, 0 = 5-K/4-6⇒0 = 5-K⇒K = 5
known this value for K you ca find the equation of thE line that pass through A and C
2) Following the same procedure in first place you calculate the slope with the points A(-2,1) Y C ( 4,5)
m= 5-1/4-(-2) = 2
now with any point A or C and the slope you obtain the line
A(-2,1)
y-y1 = m (x-x1) , Y-1= 2(X-(-2)⇒Y-1= 2X+4⇒Y=2X+4-1⇒Y =2X+3
