We can expand
Then using the product and chain rules,
Hi!
An obtuse angle is one greater than 90 degrees, a right angle one that is 90, and acute less than 90.
An obtuse triangle is one with one obtuse angle, all the rest being acute. A right triangle is one with one right angle, all the rest acute. And finally, an acute triangle is one with three acute angles.
In this case, the angles measure 83 degrees, 31 degrees, and 66 degrees. All of them are acute angles, as they're all less than 90 degrees.
Therefore, the triangle is an acute triangle.
Hope this helped!
Answer: 
Step-by-step explanation:
Distribute the negative sign. This basically changes all the signs inside the parentheses.
Combine like terms;
The answer must be C because since they are the SAME line, they must have the SAME slope
