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# Show that the Vectors → a = 3 ^ I − 2 ^ J + ^ K , → B = ^ I − 3 ^ J + 5 ^ K , → C = 2 ^ I + ^ J − 4 ^ K Form a Right-angled Triangle. - CBSE (Arts) Class 12 - Mathematics

ConceptBasic Concepts of Vector Algebra

#### Question

Show that the vectors $\vec{a} = 3 \hat{i} - 2 \hat{j} + \hat{k} , \vec{b} = \hat{i} - 3 \hat{j} + 5 \hat{k} , \vec{c} = 2 \hat{i} + \hat{j} - 4 \hat{k}$ form a right-angled triangle.

#### Solution

$\text{ Let ABC be the given triangle and }$
$\vec{AC} = \vec{b} = \hat{i} - 3 \hat{j} + 5 \hat{k}$
$\vec{CB} = \vec{a} = 3 \hat{i} - 2 \hat{j} + \hat{k}$
$\vec{AB} = \vec{c} = 2 \hat{i} + \hat{j} - 4 \hat{k}$
$\vec{a} . \vec{b} = 3 + 6 + 5 = 14$
$\vec{b} . \vec{c} = 2 - 3 - 20 = - 21$
$\vec{c} . \vec{a} = 6 - 2 - 4 = 0$
$\text{ So }, \vec{AB} \text{ is perpendicular to } \vec{CB} .$
$\text{ Thus }, ∆ABC\text{ is a right-angled triangle. }$

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Solution Show that the Vectors → a = 3 ^ I − 2 ^ J + ^ K , → B = ^ I − 3 ^ J + 5 ^ K , → C = 2 ^ I + ^ J − 4 ^ K Form a Right-angled Triangle. Concept: Basic Concepts of Vector Algebra.
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