Math Core

Unit 9 · Test

Unit 9 test: Vectors and Polar Form

15 questions. Answer them all, then submit to see your score. Solutions unlock after you submit.

This test covers vectors, the dot product, polar coordinates, graphs of polar equations, complex numbers in trigonometric form and De Moivre's theorem.

Question 1

Find the component form of the vector from P(4,−2)P(4, -2) to Q(−2,5)Q(-2, 5). Enter it as (a,b)(a, b).

Enter a point like (2, -3)

Question 2

Find the magnitude of v=7i−24j\mathbf{v} = 7\mathbf{i} - 24\mathbf{j}.

Enter a number. Fractions like 3/4 and sqrt(2) are OK.

Question 3

A vector has magnitude 1212 and direction angle 120∘120^\circ. Find its component form. Enter it as (a,b)(a, b).

Enter a point like (2, -3)

Question 4

Find ⟨5,−2⟩⋅⟨1,4⟩\langle 5, -2 \rangle \cdot \langle 1, 4 \rangle.

Enter a number. Fractions like 3/4 and sqrt(2) are OK.

Question 5

Find the angle between u=⟨1,2⟩\mathbf{u} = \langle 1, 2 \rangle and v=⟨3,−1⟩\mathbf{v} = \langle 3, -1 \rangle in degrees, rounded to the nearest tenth.

Enter a number. Fractions like 3/4 and sqrt(2) are OK.

Question 6

Find kk so that ⟨5,2⟩\langle 5, 2 \rangle and ⟨4,k⟩\langle 4, k \rangle are orthogonal.

Enter a number. Fractions like 3/4 and sqrt(2) are OK.

Question 7

Convert the polar point (6,2π3)(6, \tfrac{2\pi}{3}) to rectangular coordinates.

Enter a point like (2, -3)

Question 8

Write the rectangular point (3,−1)(\sqrt{3}, -1) in polar form with r>0r > 0 and 0≤θ<2π0 \le \theta < 2\pi. Give θ\theta in radians.

Enter a point like (2, -3)

Question 9

Which rectangular equation has the same graph as r=4cos⁡θr = 4\cos\theta?

Question 10

How many petals does the rose r=7cos⁡(6θ)r = 7\cos(6\theta) have?

Enter a number. Fractions like 3/4 and sqrt(2) are OK.

Question 11

What kind of graph is r=3+3sin⁡θr = 3 + 3\sin\theta?

Question 12

Write z=−4−4iz = -4 - 4i in trigonometric form r(cos⁡θ+isin⁡θ)r(\cos\theta + i\sin\theta) and enter (r,θ)(r, \theta), with θ\theta in degrees and 0∘≤θ<360∘0^\circ \le \theta < 360^\circ.

Enter a point like (2, -3)

Question 13

Let z1=10(cos⁡130∘+isin⁡130∘)z_1 = 10(\cos 130^\circ + i\sin 130^\circ) and z2=2(cos⁡10∘+isin⁡10∘)z_2 = 2(\cos 10^\circ + i\sin 10^\circ). Find the real part of z1z2\dfrac{z_1}{z_2}.

Enter a number. Fractions like 3/4 and sqrt(2) are OK.

Question 14

Find (1+i)4(1 + i)^4. The answer is a real number.

Enter a number. Fractions like 3/4 and sqrt(2) are OK.

Question 15

The cube roots of 8(cos⁡120∘+isin⁡120∘)8(\cos 120^\circ + i\sin 120^\circ) all have modulus 22. List their arguments in degrees, with 0∘≤θ<360∘0^\circ \le \theta < 360^\circ, separated by commas.

Separate answers with commas, e.g. 2, -5