Solving a trigonometric equation with cosine equal to negative one

Solving a trigonometric equation with cosine equal to negative one

Assessment

Interactive Video

Mathematics

11th Grade - University

Hard

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The video tutorial explains how to evaluate the cosine of an angle when it equals -1. It begins by discussing the unit circle and identifying the X coordinate where the angle intersects. The tutorial then determines the angle between 0 and 2π, which is π, and explains how to find all solutions without constraints, resulting in π plus 2πR, where R is a variable representing the number of rotations. The video concludes with a summary of the solution process.

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5 questions

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1.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

What is the x-coordinate on the unit circle when the cosine of theta is -1?

0

π

1

-1

2.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

Which angle between 0 and 2π has a cosine value of -1?

π/2

π

0

3.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

If you are asked to find all solutions for cosine of theta equals -1, what would be the general form?

π/2 + 2πR

2π + πR

π + 2πR

0 + πR

4.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

What does the variable R represent in the general solution π + 2πR?

The angle in degrees

The number of times the circle is traversed

The radius of the circle

A constant

5.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

What is the significance of adding 2π to the angle π in the context of the unit circle?

It changes the cosine value to 0

It returns to the same point on the circle

It doubles the angle

It changes the sine value to 1