All categories

3 years ago

Calculate the length of CD give your answer to 3 significant figures.

Mathematics

1 answer:

Westkost [7]3 years ago

5 0

12.7
Using the Pythagorean theorem, you can easily calculate the length of BC.
So:
BC = sqrt(12^2 - 6^2) = sqrt(144 - 36) = sqrt(108) = 10.39230485
Now consider triangle BCD. You know all three angles and one side. Using the law of sines you know that ratio of the sine of each angle over the opposite side is constant. So:
BC/sin(55) = CD/sin(90)
BC/sin(55) = CD/sin(90)
sin(90)BC/sin(55) = CD
1*BC/sin(55) = CD
BC/sin(55) = CD
10.39230485/0.819152044 = CD
12.68666167 = CD
12.7 = CD

You might be interested in

Hey guys, can you help me please

KatRina [158]

<h3>Answer: 93.382 square cm</h3>

=========================================================

Work Shown:

The green triangle in the back has height 2.6 and an unknown base x. Half of this is x/2, which I'll call y. So y = x/2.

The green triangle in the back is split along the vertical dotted line to get two right triangles. The base of each right triangle is y = x/2.

Use the Pythagorean theorem to find y. Use that to find x

a^2+b^2 = c^2

y^2+(2.6)^2 = (3.2)^2

y^2 + 6.76 = 10.24

y^2 = 10.24 - 6.76

y^2 = 3.48

y = sqrt(3.48) .... apply square root

y = 1.8654758 approximately

x/2 = 1.8654758

x = 2*1.8654758

x = 3.7309516 also approximate

The base of the triangle is roughly 3.7309516 meters

We can now find the area of one green triangle

area of triangle = base*height/2 = 3.7309516*2.6/2 = 4.85023708

two triangles have approximate area 2*(4.85023708) = 9.70047416

----------------------------------

So far we've only considered the triangular faces. There are 3 more faces which are the rectangular sides. These are known as the lateral sides.

One way to get the lateral surface area is to multiply the perimeter of the triangle by the depth of the prism

perimeter of triangle = (side1)+(side2)+(side3)

perimeter = 3.7309516 + 3.2 + 3.2

perimeter = 10.1309516

lateral surface area = (depth)*(perimeter)

lateral surface area = (8.26)*(10.1309516)

lateral surface area = 83.681660216

----------------------------------

The last step is to add this lateral surface area onto the area of the two triangles to get the full surface area

surface area = (triangular area) + (lateral surface area)

surface area = (9.70047416) + (83.681660216)

surface area = 93.382134376

surface area = 93.382 square cm

3 0

3 years ago

Read 2 more answers

Digital clocks can display how many numbers that are perfect squares

nasty-shy [4]

7

Clocks can display up to the number 59 (60 minutes in an hour). If you list all of the perfect squares that are under 59, you will find that there is 7 of them: 1, 4, 9, 16, 25, 36, and 49.

7 0

3 years ago

What is the difference? StartFraction x Over x squared minus 16 EndFraction minus StartFraction 3 Over x minus 4 EndFraction Sta

katovenus [111]

Answer:

The option "StartFraction negative 2 (x + 6) Over (x + 4) (x minus 4) EndFraction" is correct

That is $\frac{-2(x+6)}{(x+4)(x-4)}$

Therefore $\frac{x}{x^2-16}-\frac{3}{x-4}=\frac{-2(x+6)}{(x+4)(x-4)}$

Step-by-step explanation:

Given problem is StartFraction x Over x squared minus 16 EndFraction minus StartFraction 3 Over x minus 4 EndFraction

It can be written as below :

$\frac{x}{x^2-16}-\frac{3}{x-4}$

To solve the given expression

$\frac{x}{x^2-16}-\frac{3}{x-4}$

$=\frac{x}{x^2-4^2}-\frac{3}{x-4}$

$=\frac{x}{(x+4)(x-4)}-\frac{3}{x-4}$ ( using the property $a^2-b^2=(a+b)(a-b)$ )

$=\frac{x-3(x+4)}{(x+4)(x-4)}$

$=\frac{x-3x-12}{(x+4)(x-4)}$ ( by using distributive property )

$=\frac{-2x-12}{(x+4)(x-4)}$

$=\frac{-2(x+6)}{(x+4)(x-4)}$

$\frac{x}{x^2-16}-\frac{3}{x-4}=\frac{-2(x+6)}{(x+4)(x-4)}$

Therefore $\frac{x}{x^2-16}-\frac{3}{x-4}=\frac{-2(x+6)}{(x+4)(x-4)}$

Therefore the option "StartFraction negative 2 (x + 6) Over (x + 4) (x minus 4) EndFraction" is correct

That is $\frac{-2(x+6)}{(x+4)(x-4)}$

5 0

4 years ago

Read 2 more answers

X-(-6)=-2 EXPLAIN YOUR ANSWER

Zielflug [23.3K]

Answer:

If your asking for the Value of X the answer would be (-8)

Step-by-step explanation:

when your subtracting a negative, it's the same as addition, and if the equation should be equal to 2, then the answer would be (-8), because

(-8) - (-6) = -2.

8 0

3 years ago

A boat traveled 128 kilometers in

AlekseyPX

Answer:

The Distance cover by boat in 2 hours and 15 minutes is 72 km

Step-by-step explanation:

Given as :

The Distance cover by boat = 128 kilometer

The time taken is 4 hours

As , Distance = Speed ×Time

So , Speed = $\frac{Diastance}{Time}$

Or, Speed = $\frac{128 km}{4 hours}$

∴ Speed = 32 km per hour

Now, again The boat travel 2 hours and 15 minutes further with speed 32 kmph

So, Time2 = 2 + $\frac{15}{60}$

Or, Time2 = 2 + $\frac{1}{4}$

I.e Time2 = $\frac{9}{4}$ hours

Again , Distance = Speed ×Time

So , Distance = 32kmph × $\frac{9}{4}$ hours

I.e Distance = $(\frac{32\times 9}{4})$ = 72 kilometer

Hence The Distance cover by boat in 2 hours and 15 minutes is 72 km Answer

5 0

3 years ago