Trigonometric Functions and Triangle Areas

Trigonometric Functions and Triangle Areas

Assessment

Interactive Video

Mathematics

9th - 10th Grade

Hard

Created by

Patricia Brown

FREE Resource

The video tutorial explains how to derive the sine of a sum formula using a triangle with angles alpha and beta. It starts by introducing the angles and setting up a triangle. The area of the triangle is calculated using the side-angle-side formula. The tutorial then discusses the altitude of the triangle, which divides it into two right sub-triangles. By equating the areas of these sub-triangles, the sine of a sum formula is derived, showing that the sine of alpha plus beta equals the sine of alpha times the cosine of beta plus the cosine of alpha times the sine of beta.

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9 questions

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1.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

What is the range of angles alpha and beta in the triangle construction?

0 to pi

0 to pi/2

0 to 2pi

pi/2 to pi

2.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

Which formula is used to determine the area of the triangle?

Side-angle-side formula

Base times height

Heron's formula

Pythagorean theorem

3.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

What is the length of the altitude y in terms of angle alpha?

a times sine of alpha

b times sine of alpha

a times cosine of alpha

b times cosine of alpha

4.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

How is the altitude y related to angle beta in the right triangle?

y = a times cosine of beta

y = b times sine of beta

y = b times cosine of beta

y = a times sine of beta

5.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

What is the area of one of the sub-triangles in terms of angle beta?

1/2 times a times b times cosine of beta

1/2 times b times cosine of beta times sine of alpha

1/2 times a times cosine of beta times sine of alpha

1/2 times a times b times sine of beta

6.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

Which of the following is a correct expression for the area of the original triangle?

1/2 times a times b times sine(alpha + beta)

a times b times sine(alpha + beta)

1/2 times a times b times cosine(alpha + beta)

a times b times cosine(alpha + beta)

7.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

What is the relationship between the areas of the original triangle and the sub-triangles?

The original triangle's area is half the area of one sub-triangle.

The original triangle's area is twice the area of one sub-triangle.

The original triangle's area is the sum of the sub-triangles' areas.

The original triangle's area is the difference of the sub-triangles' areas.

8.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

What is the formula for the sine of a sum of two angles?

sine(alpha) + sine(beta)

cosine(alpha) + cosine(beta)

sine(alpha) times cosine(beta) + cosine(alpha) times sine(beta)

sine(alpha) times sine(beta) + cosine(alpha) times cosine(beta)

9.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

What is the significance of the sine of a sum formula in trigonometry?

It is used to determine the cosine of the sum of two angles.

It allows the calculation of the sine of the sum of two angles.

It is used to find the length of a side in a right triangle.

It helps in calculating the area of any polygon.