How to show - 1 into -5 on number line

De and f are respectively the midpoint of the side bc ca and ab of an equilateral triangle abc prove that triangle d e f is also an equilateral triangle.( plz answer by handwritten)​

Find the area of the parallelogram abcd

2. find the value of k, if the equation 2x + kay - 6y + 3x + y + 1 = 0 represents a pair of straight lines.find the point of intersection of the lines and the angle between the straight lines for this value of a​