16. which of the following are the measures of a right isosceles triangle? a. 36°, 60°, 90° b. 40°, 40°, 90° c. 60°, 60°, 60° d. 45°, 90°, 45° 17. of the following triangles, which one is impossible to construct? a. acute scalene b. acute equilateral c. obtuse scalene d. obtuse equilateral

16. 
The angles of right isosceles triangle are such that there is the right angle, 90 degrees, and there are two identical angles that add up to 90.

17. 
It is impossible to have an obtuse equilateral because and obtuse triangle has an angle that is more than 90 but less than 190. The equilateral triangle has all the angles equaling the same; 60 degrees. 60 degrees isn't obtuse so it is impossible to have an obtuse equilateral triangle. 

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