{"id":6294,"date":"2021-10-12T16:44:17","date_gmt":"2021-10-12T11:14:17","guid":{"rendered":"https:\/\/mathemerize.com\/?p=6294"},"modified":"2021-11-30T16:04:57","modified_gmt":"2021-11-30T10:34:57","slug":"two-point-form-of-a-line-equation","status":"publish","type":"post","link":"https:\/\/mathemerize.com\/two-point-form-of-a-line-equation\/","title":{"rendered":"Two Point Form of a Line Equation"},"content":{"rendered":"
Here you will learn two point form of a line equation with proof and examples.<\/p>\n
Let’s begin –<\/p>\n
\nThe equation of a line passing through two points \\((x_1, y_1)\\) and \\((x_2, y_2)\\) is <\/p>\n
\\(y – y_1\\) = (\\(y_2 – y_1\\over x_2 – x_1\\))(\\(x_2 – x_1\\))<\/p>\n<\/blockquote>\n
Proof<\/strong> : <\/p>\n
\nLet m be the slope of line passing through \\((x_1, y_1)\\) and \\((x_2, y_2)\\). Then,<\/p>\n
m = \\(y_2 – y_1\\over x_2 – x_1\\)<\/p>\n
By using point-slope form, the equation of the line is,<\/p>\n
\\(y – y_1\\) = m(\\(x_2 – x_1\\)) <\/p>\n
\\(y – y_1\\) = (\\(y_2 – y_1\\over x_2 – x_1\\))(\\(x_2 – x_1\\))<\/p>\n
This is the required equation of the line.<\/p>\n<\/blockquote>\n
Example<\/strong><\/span> : Find the equation of the line joining the points (-1, 3) and (4, -3).<\/p>\n
Solution<\/span><\/strong> : Here, the two points are \\((x_1, y_1)\\) = (-1, 3) and \\((x_2, y_2)\\) = (4, -2).<\/p>\n
So, the equation of the reuqired line is<\/p>\n
\\(y – y_1\\) = (\\(y_2 – y_1\\over x_2 – x_1\\))(\\(x_2 – x_1\\))<\/p>\n
\\(\\implies\\) y – 3 = \\(3 – (-2)\\over -1 – 4\\)(x + 1)<\/p>\n
\\(\\implies\\) y – 3 = -x – 1 \\(\\implies\\) x + y – 2 = 0.<\/p>\n
Example<\/strong><\/span> : Find the equation of the line joining the points \\((a{t_1}^2, 2at_1)\\) and \\((a{t_2}^2, 2at_2)\\).<\/p>\n
Solution<\/span><\/strong> : Here, the two points are \\((x_1, y_1)\\) = \\((a{t_1}^2, 2at_1)\\) and \\((x_2, y_2)\\) = \\((a{t_2}^2, 2at_2)\\).<\/p>\n
So, the equation of the required line is<\/p>\n
\\(y – y_1\\) = (\\(y_2 – y_1\\over x_2 – x_1\\))(\\(x_2 – x_1\\))<\/p>\n
y – \\(2at_1\\) = \\(2at_2 – 2at_1\\over {at_2}^2 – {at_1}^2\\) \\((x – a{t_1}^2)\\)<\/p>\n
y – \\(2at_1\\) = \\(2\\over t_1 + t_2\\) \\((x – a{t_1}^2)\\)<\/p>\n
\\(\\implies\\) y\\((t_1 + t_2)\\) – \\(2a{t_1}^2\\) – \\(2at_1t_2\\) = 2x – \\(2a{t_1}^2\\)<\/p>\n
\\(\\implies\\) y\\((t_1 + t_2)\\) = 2x + \\(2at_1t_2\\).<\/p>\n\n\n