Math Problem Statement

En linje l er givet ved ligningen l: y = -1/3 x + 5. En linje m er ortogonal på l. Det oplyses, at punktet P(2,10) ligger på m. a) Bestem en ligning for linjen m.

Solution

To find the equation of the line mm that is orthogonal (perpendicular) to line ll, we can proceed with the following steps:

Step 1: Identify the Slope of Line ll

The equation for line ll is: y=13x+5y = -\frac{1}{3}x + 5 The slope of line ll, mlm_l, is 13-\frac{1}{3}.

Step 2: Determine the Slope of Line mm

Since line mm is orthogonal to line ll, its slope mmm_m must be the negative reciprocal of mlm_l. Therefore, mm=11/3=3m_m = -\frac{1}{-1/3} = 3

Step 3: Use the Point-Slope Form of the Line Equation

We know that line mm passes through the point P(2,10)P(2, 10), so we can use the point-slope form of the line equation: yy1=m(xx1)y - y_1 = m(x - x_1) where (x1,y1)=(2,10)(x_1, y_1) = (2, 10) and m=3m = 3.

Substituting these values, we get: y10=3(x2)y - 10 = 3(x - 2)

Step 4: Simplify the Equation

Expanding and simplifying: y10=3x6y - 10 = 3x - 6 y=3x+4y = 3x + 4

Conclusion

The equation of line mm is: y=3x+4y = 3x + 4

Would you like further details on any step, or do you have additional questions?

Here are five questions to explore further:

  1. What would happen if line ll had a different slope?
  2. How do we determine the equation of a line given two points?
  3. Why is the negative reciprocal used for perpendicular slopes?
  4. What if the point PP was different—how would that affect the equation of mm?
  5. How can we verify if two lines are perpendicular using their slopes?

Tip: When working with perpendicular lines, remember that the slopes are always negative reciprocals of each other.

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Math Problem Analysis

Mathematical Concepts

Coordinate Geometry
Slope of a Line
Perpendicular Lines

Formulas

Slope formula for perpendicular lines: m1 * m2 = -1
Point-slope form: y - y1 = m(x - x1)

Theorems

Perpendicular Slopes Theorem

Suitable Grade Level

Grades 10-12