Question in-tri
In triangle ABC, the measure of angle A is 
. If triangle ABC is isosceles, which of the following is NOT a possible measure of angle B ?
In triangle ABC , the measure of angle A is . If triangle ABC is isosceles,
Hard-difficulty · SAT Math · Lines, Angles, and Triangles — Triangle sum theorem. Read the question above, select your answer, and check the full explanation below to understand exactly why the correct choice works.
Answer explanation
Choice D is correct. The sum of the three interior angles in a triangle is 
. It’s given that angle A measures 
. If angle B measured , the measure of angle C would be 
. Thus, the measures of the angles in the triangle would be , , and 
. However, an isosceles triangle has two angles of equal measure. Therefore, angle B can’t measure .
Choice A is incorrect. If angle B has measure , then angle C would measure 
, and , , and could be the angle measures of an isosceles triangle. Choice B is incorrect. If angle B has measure , then angle C would measure 
, and , , and could be the angle measures of an isosceles triangle. Choice C is incorrect. If angle B has measure , then angle C would measure 
, and , , and could be the angle measures of an isosceles triangle.
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