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3 years ago

Use the law of cosines to explain why c^2=a^2+b^2 for triangle ABC, where angle C is a right angle.

1 answer:

5 0

Let $c$ be the length of the hypotenuse in the right triangle $ABC$ , with $m\angle C=90^\circ$ for $\angle C$ , the angle opposite the hypotenuse.

By the law of cosines,

$c^2=a^2+b^2-2ab\cos C$

But $\cos90^\circ=0$ , so we end up with $c^2=a^2+b^2$ .

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Step-by-step explanation:

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2 years ago

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Examine the expression. 17x - 34 Which is an equivalent expression? O 17*(1 + ) O 17x (1-2) O 17+(1-1) O 17*(1 + 2)

mixer [17]

Answer:

17(x-2)

Step-by-step explanation:

Given the expression

17x - 34

We are to factorize it

Get their factors

17x = 17 * x

34 = 17 * 2

Since 17 is common to both factors, hence 17 is the GCF

17x - 34 = 17(x - 2)

Hence the equivalent expression is 17(x-2)

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2 years ago

3. A plane travels at a constant speed. It takes 6 hours to travel 3,360 miles. (20 points)

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Answer:

a. The plane's speed in mph is 560

b. At this rate, the plane can travel 5,600 miles in 10 hours.

Step-by-step explanation:

In order to find the planes speed in mph, some simple arithmetic must be done and you should divide 3,360 by 6. Now that you have determined that 3,360/6 equals 560, you know that in order to figure out how many miles the plane can travel in 10 hours, all you must do is multiply 560 by 10 which equals 5,600.

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2 years ago

Compare the values of the underlined digits (4)

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The value of 4 in 34,258 is 4,000 times the value of 4 in 47,163 is 40,000
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2 years ago

Find the longer leg of the triangle.

Paha777 [63]

Answer:

Choice A. 3.

Step-by-step explanation:

The triangle in question is a right triangle.

The length of the hypotenuse (the side opposite to the right angle) is given.
The measure of one of the acute angle is also given.

As a result, the length of both legs can be found directly using the sine function and the cosine function.

Let $\text{Opposite}$ denotes the length of the side opposite to the $30^{\circ}$ acute angle, and $\text{Adjacent}$ be the length of the side next to this $30^{\circ}$ acute angle.

$\displaystyle \begin{aligned}\text{Opposite} &= \text{Hypotenuse} \times \sin{30^{\circ}}\\ &=2\sqrt{3}\times \frac{1}{2} \\&= \sqrt{3}\end{aligned}$ .

Similarly,

$\displaystyle \begin{aligned}\text{Adjacent} &= \text{Hypotenuse} \times \cos{30^{\circ}}\\ &=2\sqrt{3}\times \frac{\sqrt{3}}{2} \\&= 3\end{aligned}$ .

The longer leg in this case is the one adjacent to the $30^{\circ}$ acute angle. The answer will be $3$ .

There's a shortcut to the answer. Notice that $\sin{30^{\circ}} < \cos{30^{\circ}}$ . The cosine of an acute angle is directly related to the adjacent leg. In other words, the leg adjacent to the $30^{\circ}$ angle will be the longer leg. There will be no need to find the length of the opposite leg.

Does this relationship $\sin{\theta} < \cos{\theta}$ holds for all acute angles? (That is, $0^{\circ} < \theta$ ?) It turns out that:

$\sin{\theta} < \cos{\theta}$ if $0^{\circ} < \theta$ ;
$\sin{\theta} > \cos{\theta}$ if $45^{\circ} < \theta$ ;
$\sin{\theta} = \cos{\theta}$ if $\theta = 45^{\circ}$ .

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2 years ago

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