Question

Geometry help

http://tinypic.com/r/fw663d/6

1. Calculate the length of DE
2. Calculate the area of circle Q
3. Approximate the area of the circle segment bounded by segement DE and arc DE
4. Calculate the circumfrence of circle Q
5. Calculate the area or the sector bounded by segment DQ, segment EQ and arc DE

Answer 1

1) use the rule of cosines
2)pi(15)squared
3)since the area of the sector is (72pi/180)(15squared)/2, and you can calculate the area of the triangle through the equation 15*15*sin(72degrees), deducting them, should give you the area you want

Answer 2

4)2pi(15)=30pi
5)They are either kidding or they are trying to test your skill for spotting pentagons, since the angle given is 72 degrees. Using that, you can also find the answer in part 3 and then you can answer part 5.
which grade is this question for?

Answer 3

What is the rule of cosines?

Answer 4

in a circle with sides abc the length of the side c facing angle theta is equal to :
(a squared)+(b squared)-ab costheta

Answer 5

sorry, there is a small mistake, you should have :
-2ab costheta instead of -ab
I forgot about the coefficient of 2

Answer 6

did you get the last note? IT SHOULD BE
c=(a squared)+(b squared)-2ab cos theta

Answer 7

confirm that you understood the right form

Answer 8

Yes. Hold on for a minute im gonna solve it

Answer 9

Is it 10.8 pi?

Answer 10

I missed something its calculate the arc of DE

Answer 11

which part?

Answer 12

arc of DE is r*theta [theta in radians]
arc DE=15*72pi/180

Answer 13

the answer for DE is 31.4159 which is 10pi

Answer 14

Number 3 im getting 213. something which isnt the anwser. Can you show me the steps?

Answer 15

wait a sec

Answer 16

1) find the area of the triangle.
2) multiply it by 5 to find the area of the pentagon inside the circle
3) deduct the area of the circle from the area of the pentagon
4) divide that result of subtraction from step 3 by 5
5) the answer is the area of the portion between the arc and the side of the triangle facing the angle 72.

Answer 17

tell me whether that works or not

Answer 18

Number 1 I got 10.8 pi
Number 2 I got 225 pi
Number 3 I got 34.4 pi
Number 4 i got 30 pi
Number 5 I got 6 pi

Do those look right to you?

Answer 19

1)I'm not sure how you're finding it, but I found it to be 17.63, using law of cosines
2) correct
wait for the rest....

Answer 20

3)34.377819
4)correct
5)sum the area you found to solve for part 3 (106.99385) with the final answer of part 3. the result would be 141.371669

Answer 21

let me check my answers using another way...

Answer 22

yes, it is perfectly correct

Answer 23

tell me your doubts

Answer 24

I remembered one more thing,
The equation provided for law of cosines is equal to square of the length of that side. Therefore, to get the length, you have to take the square root of that equation. OK?

Answer 25

Good luck

Answer 26

Thank you for the help