1) given
2) definition of linear pair
3) definition of linear pair and supplementary
4) definition of supplementary supplementary angles add to 180
5) the measure of angle one plus the measure of angle 2 plus the measure of angle 3 equals 180
6) substitution in lines 4 and 5
7) the measure of angle one plus the measure of angle 2 equals measure of angle 4 by algebra and simplification
Answer:

Step-by-step explanation:
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For line B to AC: y - 6 = (1/3)(x - 4); y - 6 = (x/3) - (4/3); 3y - 18 = x - 4, so 3y - x = 14
For line A to BC: y - 6 = (-1)(x - 0); y - 6 = -x, so y + x = 6
Since these lines intersect at one point (the orthocenter), we can use simultaneous equations to solve for x and/or y:
(3y - x = 14) + (y + x = 6) => 4y = 20, y = +5; Substitute this into y + x = 6: 5 + x = 6, x = +1
<span>So the orthocenter is at coordinates (1,5), and the slopes of all three orthocenter lines are above.</span>
A is correct, D, And E.....
Check the picture below.
well, since the triangle is an isosceles, with twin sides and twin angles at the "base", let's check what the angle at R is, 15(7) - 31 = 74, and her twin sister at T is also 74, that means that the angle at S is 180 - 74 - 74 = 32.