Can someone please help me

a = 84°

Step-by-step explanation:

∠ QPR and ∠ TPR are adjacent and supplementary, thus

∠TPR = 180° - 123° = 57°

Given there are parallel lines , then

∠ PTR = 27° ( alternate angle )

The external angle of a triangle is equal to the sum of the 2 opposite interior angles.

∠ TRS is an external angle , thus

∠ TRS = a = 57° + 27° = 84°

84 degrees.

Step-by-step explanation:

m < R + m < T = 123  (External angle of a triangle theorem)

m < T =  27 degrees (alternate angle to 27 degrees).

So m < R = 123 - 27 = 96 degrees.

Finally m < a = 180 - 96 = 84 degrees  ( as it is adjacent to < R)

step-by-step explanation:

points a and b are equidistant from the desired line, so the line you find by using them will go through point r.

using points other than a and b will give the desired line only if they are equidistant from r. if they are randomly located, the perpendicular line you create will not necessarily go through point r, hence will not be a solution to the problem.