Answer:
80
Step-by-step explanation:
180-(60+40)=180-60-40=180-100=80
The only shape that has that much is a decagon 10 sides. t<span>he </span>sum<span> of the interior </span>angles of a Regular Decagon is 1440 degrees.
First, let's expand the right side. Now our equation is

Now, we gather all the terms with x in it on the left side, and the numbers without x on the right. We get:

And then we can make this

We divide both sides by 12 to get x on its own, so x = 13/12 or 1.08
let the line between 2 tria be y
sin 60/8√2 = sin 90/y
y=13.06
sin 45/13.06 = sin 90/x
x=18.46