Four triangles are shown. One side of each triangle lies on a ray, and the triangles are not drawn to scale. Based on these triangles, which statement about x is true?

Choice a :  x= 102 degrees because 180°- (63°+39° ) = 78° and 180° - 78° = 102°

Step-by-step explanation:

Two angles are given as  63° and 39°

To find the third angle we subtract the other two angles from 180°

180°- 63°-39° gives 78°as the third inner angle .

The third angle and the outer angle x lie on the straight line making a total of 180°.

To find x we again subtract the inner angle 78° from 180°.

This gives the value of x to be 102°

180°- 78°=102°

Choice a is the best option.

Step-by-step explanation:

check the picture below.

well, the angle at the vertex d is clearly not a right-angle, let's check for the one at the vertex f which does look like,   however if it's indeed, that means ef is perpendicular to df, in which case their slopes will be negative reciprocal of each other.

so the negative reciprocal of the slope of ef is 1, however the slope of df is not 1, is 1/2, so nope, they're not perpendicular lines.