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Exterior and Interior angles?

How do I work them out in a triangle?

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Since writing this post Megan :) may have helped people, but has not within the last 4 days. Megan :) is a verified member, has been around for 3 years, 3 months and has 63 posts and 151 replies to their name.

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Interior angles are the angles between two sides measured from inside the triangle. External angles are the same but measured outside the triangle (out and around the corner of the triangle).

Interior angles add up to 180degrees always for a triangle.

Help me with: Insignificance.

Yes, but what’s the formula?

A+B+C=180

Help me with: Insignificance.

I mean whats the formula to work out an interior angle of a triangle haha

Are you talking about the sine and cosine rules? To work out the interior angles of a triangle from the length of the sides and an angle.

Help me with: Insignificance.

No haha, its on mymaths.
There is like 6 triangles and we already have 2 angles.
I know how to work out exterior angles, just not interior :/

o.O
So you have two interior angles? So the other angle is 180-(A+B)

Or are the angles exterior angles and you need the interior ones?

Help me with: Insignificance.

I’ll give you an example :L
Right on question 2 there is 2 exterior angles, one is 145 degress and the other is 75.
It tells me to work out the angle labelled ‘x’, which is the interior angle…

I think you got those the wrong way round. You cannot have an exterior angle of 75degrees on a triangle. You can’t have an exterior angle of 145degrees either.

Help me with: Insignificance.

Well thats what it says :/

Well if that’s what it say then it is wrong. Exterior angles must be less than more than 180degrees.

Help me with: Insignificance.

:S
I’ve just reloaded it so I’ve got a new set of questions
http://i55.tinypic.com/14c9seq.jpg
Just to show you what I mean :)

Yeah I thought that’s what you meant. x is strictly not the exterior angle, but I see where the question is coming from.

Well you know there are 180 degrees in a straight line. Standing on a point on the line, looking along the line, you have to turn 180 degrees to face where the line came from. So if you know the angle inside is say y degrees, then the angle outside the triangle is 180-y.

To work out the top left one, find the missing interior angle, which is 180-(49+44)=87degrees. The angle marked outside is then 180-87=93degrees.

For something like the top middle one, the two angles corresponding to 144 and 73 are, 180-144=36 and 180-73=107. So these are two interior angles of the triangle. x must then be 180-(36+107)=37degrees.

Make sense?

Help me with: Insignificance.

err, sorta :/

So how would I do the top left one?
180-(101+52)=27
180-27=153?

I mean the top right one, haha

MeganS wrote:
180-(101+52)=27

No, you can add exterior and interior angles that way.

You can work out the angle that goes inside 101. And then you can work out the angle that goes inside x. And then you can work out x from that.

Help me with: Insignificance.

I’m sorry that made no sense to me what so ever :L

You’ll have to have a play about with the numbers then and see if you can work them out.

Help me with: Insignificance.

:/

Sorry, I’m not going to tell you the answer. They’re not difficult questions, you just need a little practice solving them.

A little tip for the last two questions. The triangle sides with a short line through them, in case you don’t know, this means the triangles are isosceles, and the two sides with with the short line through them have the same length. That means the two angles at the base of the triangle are the same.

Help me with: Insignificance.

Well could you tell me how to work out the interior angle of a polygon when it has 9 sides?
I’ve worked out the exterior which is 30 because 360/9=30

The sum of internal angles of a triangle is 180degrees.

For any polygon, you can split it up into triangles. A nonagon can be split into seven triangles, so the internal angles of a nonagon are the sum of the internal angles of the triangles that make it up. So 7×180=1260degrees.

Have a looksie here;
http://www.mathsisfun.com/geometry/in…

Help me with: Insignificance.

Right, this is a new sheet i’m on.
There is 12 sides, so if I did 10×180 that equals 1800 degress, but it won’t let me type 4 digit answers in the box, only three :/

on that my maths, how do you do the bottom right one the 122 angle???

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I Can’t Do This Too Im On Mymaths Too I Need Help :/

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Megan you have to do 360 divided by the amount of sides and there is you answer!!!

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