I need help with this. I have tried using the formula they gave me in my lesson, but it came out with the wrong answer.

Can someone help me?

Question

I need help with this. I have tried using the formula they gave me in my lesson, but it came out with the wrong answer. 

Can someone help me?

anonymous · Answer

attachment

phi · Answer

what formula did you use ?

anonymous · Answer

(n-2) times 180 degrees divided by n

campbell_st · Answer

well you are looking at an irregular hexagon

the angle sum is    Angle Sum = 180 x ( n - 2)

where n = 6    

so the angle sum is 720 degrees 

so using what is shown in the question you have 

$$720 = 138 + 128 + 10x -4 + 10x -4 + 5x + 8 + 5x + 8$$

collect the like terms and then solve for x.

phi · Answer

yes, so where did you go off the tracks?    6-4 = 4  and 4*180= 720 degrees
the sum of the internal angles is 720 .

anonymous · Answer

I thought the numbers in the parentheses was the number of sides minus 2.

phi · Answer

it is.  I count 6 sides.  Don't you ?

phi · Answer

I just notice you posted
(n-2) times 180 degrees divided by n

the divide by n  gives you the internal angle if you have a *regular* figure.
(where all the angles are the same)

in this problem,  all you know is that the sum of the internal angles (which are different)  add up to (n-2)*180 = (6-4)*180= 4*180= 720

phi · Answer

For example, if you have a triangle with 3 sides, the sum of the internal angles is 
(3-2)*180= 1*180= 180
if you have an *equilateral triangle* (where all the internal angles are the same)
then the internal angle is  (n-2)*180/n  =  (3-2)*180/3 = 180/3 = 60

in this problem,  all we know is the sum of internal angles add up to 720. But the internal angles are not all the same

phi · Answer

so do what campbell posted,  add up the internal angles and set that sum equal to 720

anonymous · Answer

Alright. I'll do that.

anonymous · Answer

274 + 30x = 720

campbell_st · Answer

now just solve for x

anonymous · Answer

14.8?

anonymous · Answer

So it's 14.8? Or is there more to the problem than that?

campbell_st · Answer

that seems to be close

$$x = \frac{720 - 272}{30}$$

anonymous · Answer

I did that and I got 14.9?

campbell_st · Answer

oops slight typo its 

$$x = \frac{720 - 274}{30}$$

campbell_st · Answer

but rounded to 1 decimal place its still 14.9 degrees

anonymous · Answer

So is that what it is?

campbell_st · Answer

yep... thats the size of x, I don't know what the question was... if you need to find the angles 

then its 10*14.9 -4      and 5 * 14.9 + 8

and I don't know how accurate you answer needs to be... as in how many decimal places.

anonymous · Answer

I had to find the measure angle of F. Sorry. I should have posted that to begin with

campbell_st · Answer

so F = 10x - 4

     F = 10*(14.867) - 4

just depends on the level of accuracy.. but the method above is correct.

phi · Answer

you are on the right track but I get
30x +270= 720
(not 274)

anonymous · Answer

So I do that?

phi · Answer

if you simplify
720=134+128+10x−4+10x−4+5x+8+5x+8
you should get
720 = 262 +30x + 8  or
720 = 270 + 30x

or
30x = (720-270)
30 x= 450

can you find x and then the angle you want ?

anonymous · Answer

I have to find what Angle F equals.

phi · Answer

30 x= 450

can you find x and then the angle you want ?

phi · Answer

to find x, divide both sides of the equation by 30

anonymous · Answer

For that, I got 15.

phi · Answer

ok now angle F = 10*x - 4
what is 10 times 15 then take away 4 ?

anonymous · Answer

146

phi · Answer

yes

anonymous · Answer

That's the anwer?

phi · Answer

yes.   Think over what you did...

you found x to be 15

then you see angle F= 10*x -4
you replaced x with its value of 15
and simplified   to get
angle F= 10*15 -4 = 150-4 = 146 degrees

all done

anonymous · Answer

Thank you so much.