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3 years ago

Help with these math exercises, please!

Mathematics

1 answer:

lions [1.4K]3 years ago

4 0

1) (3-x) x (3+x)

2) 5(5-x) x (5+x)

3) (3v-wy) x (3v+wy)

4) 2(k-m) x (k+m) x (k^2+m^2)

5) (ab-4c) x (ab+4c)

Brainliest?

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The circle has a diameter of 16.
The formula for the circumference of a circle is diameter*pi
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What is the approximate surface area of a cylinder with a radius of 3 inches and a height of 10 inches?

xxMikexx [17]

245in^2

Curved surface = 2pi x r x h = 2 x 3.1 x 3 x 10 = 186
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3 years ago

If neither a nor b are equal to zero, which answer most accurately describes the product of (a + bi)(a - bi)?

Scrat [10]

Answer: the correct option is

(D) The imaginary part is zero.

Step-by-step explanation: Given that neither a nor b are equal to zero.

We are to select the correct statement that accurately describes the following product :

$P=(a+bi)(a-bi)~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~(i)$

We will be using the following formula :

$(x+y)(x-y)=x^2-y^2.$

From product (i), we get

$P\\\\=(a+bi)(a-bi)\\\\=a^2-(bi)^2\\\\=a^2-b^2i^2\\\\=a^2-b^2\times (-1)~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~[\textup{since }i^2=-1]\\\\=a^2+b^2.$

So, there is no imaginary part in the given product.

Thus, the correct option is

(D) The imaginary part is zero.

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3 years ago

An equilateral triangle with side lengths of 8.7 centimeters is shown. An apothem has a length of a and the radius has a length

Anna007 [38]

The image of the triangle is missing, so i have attached it.

Also, the options are;

A) The apothem can be found using the Pythagorean theorem.

B) The apothem can be found using the tangent ratio.

C) The perimeter of the equilateral triangle is 15 cm.

D) The length of the apothem is approximately 2.5 cm.

E) The area of the equilateral triangle is approximately 65 cm².

Answer:

Options A, B & D are true

Step-by-step explanation:

A) We are told that the triangle is an equilateral triangle.

Thus, the 3 sides equal 8.7 cm.

Now from the image, b is half of one of the sides.

Thus, b = 8.7/2 = 4.35 cm

Now, we want to find the apothem "a".

Using Pythagoras theorem, we have;

a² + 4.35² = 5²

a² = 25 - 18.9225

a² = 6.0775

a = √6.0775

a ≈ 2.5 cm.

Thus, option A is true as pythagoras theorem was able to calculate the apothem "a"

B) since the main triangle is equilateral, it means each angle is 60°.

Now,the radius line from one corner point to the centre will divide the 60° angle into 2 equal parts.

Thus, the angle made by the radius line with the base of the triangle is 60/2 = 30°

Now,from tangent ratios, we know that;

Opposite/Adjacent = tan θ

In the small triangle, opposite is apothem "a" while adjacent is b = 4.35 cm

Thus;

a/4.35 = tan 30

a = 4.35 tan 30

a ≈ 2.5 cm.

Thus, option B is correct as Tangent ratio can be used to find the apothem

C) The perimeter of equilateral triangle = 3x

Where x is length of one side.

One side is 8.7 cm

Thus, perimeter = 3 × 8.7 = 26.1 cm

Thus option C is not correct.

D) From calculations above, we saw that in both options A & B, the apothem is approximately 2.5 cm.

Thus, option D is true.

E) Area of triangle is;

A = ½ × base × height

Base = 8.7 cm

To get height, we will use trigonometric ratio. Thus;

h/8.7 = sin 60°

h = 8.7 sin 60°

Thus;

A = ½ × 8.7 × 8.7 sin 60°

A = 32.77 cm²

Thus is not equal to 65 cm². Thus, option E is not correct.

8 0

3 years ago