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Determinants and Volumes

Determinants and Volumes

1. Introduction

Introduction

2. Parallelograms and Paralellepipeds

Parallelograms and Paralellepipeds

3. Determinants and Volumes

Determinants and Volumes

4. Volumes of Regions

Volumes of Regions

5. Which parallelogram is flat?

Each pair of vectors below determines a parallelogram in R2\mathbb{R}^2. Which pair determines a parallelogram of area 00?

6. What a negative determinant means

A 3×33\times 3 matrix AA has det⁡(A)=−2\det(A) = -2, and T(x)=AxT(x) = Ax is the corresponding matrix transformation. Which statement about the image of the unit cube is correct?

7. Area from the columns

A 2×22\times 2 matrix AA has det⁡(A)=7\det(A) = 7. What is the area of the parallelogram determined by the columns of AA? Enter a number.

8. Area of a triangle

Find the area of the triangle with vertices (0,0)(0,0), (3,1)(3,1) and (1,4)(1,4). Enter a number or a fraction, for example 3/2.

9. Area factor of polar coordinates

The polar change of variables is x=rcos⁡θx = r\cos\theta, y=rsin⁡θy = r\sin\theta, with Jacobian matrix

(∂x/∂r∂x/∂θ∂y/∂r∂y/∂θ).\left(\begin{array}{cc} \partial x/\partial r & \partial x/\partial\theta \\ \partial y/\partial r & \partial y/\partial\theta \end{array}\right).

Enter the determinant of that matrix - the factor by which the change of variables scales area - as an expression in rr.

10. In your own words

In your own words, state the single most important definition or theorem of this section, and explain what it says.

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