Mathematics Grade 10 15 min

Find the magnitude of a vector

Find the magnitude of a vector

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Introduction & Learning Objectives

Learning Objectives Define a vector and its magnitude. Identify the components of a vector in two and three dimensions. State the formula for the magnitude of a 2D vector and explain its connection to the Pythagorean theorem. Accurately calculate the magnitude of a 2D vector given its components. State the formula for the magnitude of a 3D vector. Accurately calculate the magnitude of a 3D vector given its components. Interpret the magnitude of a vector in a simple real-world context, such as distance or speed. If a drone flies 3 kilometers east and then 4 kilometers north, how far is it from its starting point in a straight line? 🚁 This tutorial will teach you how to find the 'magnitude' of a vector, which is just a mathematical term for its length or size. Yo...
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Key Concepts & Vocabulary

TermDefinitionExample VectorA mathematical object that has both magnitude (size) and direction. It is often represented as an arrow or in component form.A displacement of `<3, 4>` represents a movement of 3 units to the right and 4 units up. ScalarA quantity that has only magnitude, but no direction.A speed of 10 m/s, a distance of 5 km, or a temperature of 20°C. MagnitudeThe length or size of a vector. It is a scalar quantity and is always non-negative. The notation for the magnitude of a vector **v** is ||**v**||.If a velocity vector is `<0, -50>`, its magnitude is 50 km/h. Component Form (2D)A way to write a vector using its horizontal (x-component) and vertical (y-component) parts.The vector **v** = <x, y> = <-2, 5> moves 2 units left and 5 units up. Component...
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Core Formulas

Magnitude Formula for a 2D Vector For a vector **v** = <x, y>, the magnitude is ||**v**|| = \sqrt{x^2 + y^2} Use this formula when you have a two-dimensional vector (with an x and y component) and you need to find its length. This is a direct application of the Pythagorean theorem. Magnitude Formula for a 3D Vector For a vector **w** = <x, y, z>, the magnitude is ||**w**|| = \sqrt{x^2 + y^2 + z^2} Use this formula when you have a three-dimensional vector (with x, y, and z components). It is an extension of the 2D formula, often called the distance formula in three dimensions.

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Sample Practice Questions

Challenging
A ship sails 90 miles East and then 120 miles North. What is the magnitude of the ship's displacement vector from its starting point?
A.210 miles
B.150 miles
C.30 miles
D.22500 miles
Challenging
Given vectors u = <1, 2, 2> and v = <1, -5, 4>, what is the magnitude of the resultant vector r = u + v?
A.√53
B.6
C.7
D.49
Challenging
Calculate the magnitude of the vector v = <-8/17, 15/17>.
A.1
B.23/17
C.17
D.289

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