Question

What is the value of x?
http://i.imgur.com/ilqdNQy.jpg

Answer 1

Anyone going to help?

Answer 2

@mathmale

Answer 3

That angle 71 degrees and its mate on the other side of that slanting line are "supplementary angles;" they add up to 180. What is the "supplementary angle" of 71 degrees?

Answer 4

109

Answer 5

When we add together all the interior angles of a triangle, what sum do we obtain?

Answer 6

208

Answer 7

Oops, sorry 180

Answer 8

That was a general question. Take any triangle and add up all of its 3 interior angles. The sum will be the same for any triangle. What is it? Not 208.

Answer 9

180

Answer 10

You know 2 of the 3 angles in the given triangle. How would you find the 3rd angle?

Answer 11

I don't know. That's why I'm asking here.

Answer 12

I guess it would be 81?

Answer 13

add up 71 and 81 and 109. Your result?

Answer 14

261.

Answer 15

My mistake. sorry.

what are the 3 interior angles? One of them you found earlier: (180-71) = 109.
the 2nd is 28. add 109 and 28 together. subtract the sum from 180. x=?

Answer 16

x = 81 as I said.

Answer 17

Doesn't that solve this problem for you?
if 109+81+28 add up to 180 degrees, you've got it.

Answer 18

You can use the exterior angle theorem, which states that the non-adjacent angles of the exterior angle can be added together to get to the exterior angle.

For example: