This is a test of commonsense with single/multi-choices. Complete the next sentence:

How to determine a right triangle
Align a protractor on one side of a triangle.
Measure the angle by relating to an adjacent segment.
Check the measurement to see if it is 90.

Select from the following.
(a). Point the protractor at a hexagonal point to the east or west nearest the triangle, when left-pointing, is the default point. ( a ) Fx = 17-39.;
(b). If it is 90, it is a right triangle. Remember that you just need one right angle to have right triangle.;
(c). Align another segment of the same angle on one side. Mark the angle about 1/15.;
(d). This divides a triangle into two segments with a 90 degree angle. The angle is calculated based on a number of degrees taken between the two segments.;
The answer is:
(b).