Help ! please ! with 13, 14, 15, 16, 17, 18, 19, 20, 21,

Me! #1 write an equation for the interior angles of this triangle that uses the triangle sum theorem. #2 what is the value of x? #3 what is the measure of #4 classify the triangle above as acute, obtuse, or right. state your reason in a complete sentence.

The ratio of the measures of the three angles in a triangle is 2: 9: 4. find the measures of the angels

Prove that 16^4-2^13-4^5 is divisible by 11.