6.1 Revise of Important Concept (Straight Line)

(A) Equation of a straight Line 

 An equation of straight line is given by y = mx + c.
• The variables x and y are linearly related
• The term c is known as y-intercept. It represents the y value where the line cuts the y-axis
• The term m is the gradient of the straight line and its value is constant

(B) Gradient of a Straight Line
If the points $A(x_1,y_1)$  and $B(x_2,y_2)$   lie on the straight line $y=mx+c$ , then gradient of ,the straight line
$$m=\frac{y_2-y_1}{x_2-x_1}or\frac{y_1-y_2}{x_1-x_2}$$

(C) Mid Point 



Mid Point AB is given by $$M=\left(\frac{x_1+x_2}{2},\frac{y_1+y_2}{2}\right)$$

(D) Distance Between Two Points
Distance between point $A(x_1,y_1)$ and point is $B(x_2,y_2)$ given by $$\sqrt{{\left(x_1-x_2\right)}^2+{\left(y_1-y_2\right)}^2}$$