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If D(3,-2) , E(-3,1) and F(4,-3) are the...

If D(3,-2) , E(-3,1) and F(4,-3) are the mid-points of the sides BC, CA and AB respectively of `Delta ABC` , find the co-ordinates of point A , B and C .

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To find the coordinates of points A, B, and C given the midpoints D(3, -2), E(-3, 1), and F(4, -3) of triangle ABC, we can use the midpoint formula. The midpoint M of a line segment joining points (x1, y1) and (x2, y2) is given by: \[ M = \left( \frac{x1 + x2}{2}, \frac{y1 + y2}{2} \right) \] Let’s denote the coordinates of points A, B, and C as A(x1, y1), B(x2, y2), and C(x3, y3). ### Step 1: Set up equations using the midpoint formula 1. For midpoint D(3, -2) which is the midpoint of BC: \[ D = \left( \frac{x2 + x3}{2}, \frac{y2 + y3}{2} \right) \] This gives us two equations: \[ \frac{x2 + x3}{2} = 3 \quad \text{(1)} \] \[ \frac{y2 + y3}{2} = -2 \quad \text{(2)} \] 2. For midpoint E(-3, 1) which is the midpoint of AC: \[ E = \left( \frac{x1 + x3}{2}, \frac{y1 + y3}{2} \right) \] This gives us two more equations: \[ \frac{x1 + x3}{2} = -3 \quad \text{(3)} \] \[ \frac{y1 + y3}{2} = 1 \quad \text{(4)} \] 3. For midpoint F(4, -3) which is the midpoint of AB: \[ F = \left( \frac{x1 + x2}{2}, \frac{y1 + y2}{2} \right) \] This gives us the last two equations: \[ \frac{x1 + x2}{2} = 4 \quad \text{(5)} \] \[ \frac{y1 + y2}{2} = -3 \quad \text{(6)} \] ### Step 2: Solve the equations Now, we will solve these equations step by step. **From equation (1):** \[ x2 + x3 = 6 \quad \text{(7)} \] **From equation (2):** \[ y2 + y3 = -4 \quad \text{(8)} \] **From equation (3):** \[ x1 + x3 = -6 \quad \text{(9)} \] **From equation (4):** \[ y1 + y3 = 2 \quad \text{(10)} \] **From equation (5):** \[ x1 + x2 = 8 \quad \text{(11)} \] **From equation (6):** \[ y1 + y2 = -6 \quad \text{(12)} \] ### Step 3: Substitute and solve for x-coordinates From equation (7) \(x3 = 6 - x2\). Substitute \(x3\) into equation (9): \[ x1 + (6 - x2) = -6 \implies x1 - x2 = -12 \implies x1 = x2 - 12 \quad \text{(13)} \] Now substitute \(x1\) from (13) into equation (11): \[ (x2 - 12) + x2 = 8 \implies 2x2 - 12 = 8 \implies 2x2 = 20 \implies x2 = 10 \] Now substitute \(x2 = 10\) into (13): \[ x1 = 10 - 12 = -2 \] Now substitute \(x2 = 10\) into (7): \[ x3 = 6 - 10 = -4 \] ### Step 4: Solve for y-coordinates From equation (8) \(y3 = -4 - y2\). Substitute \(y3\) into equation (10): \[ y1 + (-4 - y2) = 2 \implies y1 - y2 = 6 \implies y1 = y2 + 6 \quad \text{(14)} \] Now substitute \(y1\) from (14) into equation (12): \[ (y2 + 6) + y2 = -6 \implies 2y2 + 6 = -6 \implies 2y2 = -12 \implies y2 = -6 \] Now substitute \(y2 = -6\) into (14): \[ y1 = -6 + 6 = 0 \] Now substitute \(y2 = -6\) into (8): \[ y3 = -4 - (-6) = 2 \] ### Final coordinates Thus, the coordinates of points A, B, and C are: - \( A(-2, 0) \) - \( B(10, -6) \) - \( C(-4, 2) \) ### Summary of Results - A = (-2, 0) - B = (10, -6) - C = (-4, 2)
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