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How do you find the magnitude of a vector from its components?

To find the magnitude of a vector from its components, you calculate the square root of the sum of the squares of those components. This process effectively measures the Euclidean length of the vector in the coordinate plane.

Conditions

  • The vector is defined by its components in a 2D Cartesian coordinate system.
  • The coordinate system is orthonormal.

Reasoning, step by step

  1. Write down the vector components, e.g., a⃗=(x,y)\vec{a} = (x, y).
  2. Square the x-component: x2x^2.
  3. Square the y-component: y2y^2.
  4. Add the squared values: x2+y2x^2 + y^2.
  5. Take the square root of the sum: x2+y2\sqrt{x^2 + y^2}.
  6. Simplify the result if possible.

Example

Given a⃗=(5,−3)\vec{a}=(5,-3), compute ∥a⃗∥=52+(−3)2=25+9=34\|\vec{a}\| = \sqrt{5^2 + (-3)^2} = \sqrt{25 + 9} = \sqrt{34}.

Common misconceptions

  • Forgetting to square the components before adding.
  • Taking the square root of each component separately instead of the sum.

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