Answer:
a) m = 60°, n = 30°
b) m = 20°, n = 45°
Explanation:
a)
The top and bottom horizontal lines are parallel, so angle m is an alternate interior angle congruent to the interior angle(s) of the equilateral triangle. Those angles are all 60°.
Angle n is the complement of angle m, so is 90°-60° = 30°
m = 60°, n = 30°
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b)
The base angles of the isosceles right triangle are n = 45°. (This should be a memorized fact. It is computed as (180° -90°)/2 = 45°.)
The base angles of the isosceles acute triangle are (180°-50°)/2 = 65°. Angle m is the difference between one of these and angle n.
m = 65° -45° = 20°
m = 20°, n = 45°
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Additional comment
The sum of angles of a triangle is 180°. The "base" angles of an isosceles triangle (one with two equal sides) are equal. If 'a' is the third angle, and 'b' are the base angles, you have ...
a + 2b = 180°
2b = 180° -a
b = (180° -a)/2 . . . . . . the relation used above