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VLD [36.1K]
4 years ago
12

different sizes of regular pentagons are used in a stained glass window.each small pentagon has side lengths of 4 inches and an

area of 27.5 square inches.each large pentagon has a side lengths of 8 inches.what is the area of each large pentagon?
Mathematics
1 answer:
Liula [17]4 years ago
7 0
The goal is to find the area of a pentagon with side length 8.

We can find the area of a pentagon very easily by splitting it up into 10 congruent right triangles with the apothem as the height. The base of one of these triangles would be 4. The base angle would be 54 degrees, because it's half of the angle of a regular pentagon.

Using trig we find that the height of this triangle/apothem of the pentagon is equal to 4tan(54 degrees), which is about 5.506.

The area of a triangle is bh/2, so...4*5.506/2 = 11.011 in².
Times 10 triangles is 110.11 in².

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How do I construct angle XYZ with a measure of 2 times the measure of angle ABC
Serjik [45]
I can’t understand why everyone complicates this question. It can be easily solved by similar triangles.


In this png, we have something to make sure.

∠B=∠DAB
∠
B
=
∠
D
A
B
(Yes, dab)

This also means AD=BD
A
D
=
B
D
.

This is our basic construction of D, which is going to help us.

∠ADC=∠DAB+∠B=2∠B=∠CAB
∠
A
D
C
=
∠
D
A
B
+
∠
B
=
2
∠
B
=
∠
C
A
B

∠CAD=∠CAB−∠DAB=∠B
∠
C
A
D
=
∠
C
A
B
−
∠
D
A
B
=
∠
B

These are based on the fact that ∠A=2×∠B
∠
A
=
2
×
∠
B

Actually these conditions suffice. Because I am just proving that △ACD∼△BCA
△
A
C
D
∼
△
B
C
A

Similarity makes us realize the following:

ACBC=ADAB
A
C
B
C
=
A
D
A
B

and

ACBC=CDAC
A
C
B
C
=
C
D
A
C

So

AC×AB=BC×AD
A
C
×
A
B
=
B
C
×
A
D

and

AC2=BC×CD
A
C
2
=
B
C
×
C
D

So

BC2=BC×(BD+CD)=BC×(AD+CD)
B
C
2
=
B
C
×
(
B
D
+
C
D
)
=
B
C
×
(
A
D
+
C
D
)

=AC×AB+AC2
=
A
C
×
A
B
+
A
C
2

Q.E.D.
2.4k Views ·
6 0
3 years ago
B. How was the original $20,000 investment split between the two interest rates?
Roman55 [17]

Answer:

t + f = 2000

let  represent the amount invested at three percent; let f represent the amount invested at five percent. The total of these amounts is $20,000. The total of the interest earned by each amount is $800. Of course the interest earned is the amount multiplied by the interest rate.

4 0
3 years ago
Which polygon in the diagram cannot be mapped onto the others by similarity transformations?
Rom4ik [11]

Answer:   B.) PQRST


Step-by-step explanation:

There are no options but if its the same question I just had on a test then this is the answer..

Hope this helps..

6 0
3 years ago
Mike ran 1 mile in 4 minutes. How far did he run in 10seconds?
MrRissso [65]

Answer:

0.015 miles

Step-by-step explanation:

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3 0
4 years ago
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Stella [2.4K]

Answer: The equation in slope-intercept form is y=2x-11

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Hope this helps!

5 0
3 years ago
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