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Geometry and Trigonometry Difficulty: Hard

A line intersects two parallel lines, forming four acute angles and four obtuse angles. The measure of one of these eight angles is 7x-250°. The sum of the measures of four of the eight angles is k°. Which of the following could NOT be equivalent to k , for all values of x ?

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Explanation

Choice A is correct. It’s given that a line intersects two parallel lines, forming four acute angles and four obtuse angles. Since there are two parallel lines intersected by a transversal, all four acute angles have the same measure and all four obtuse angles have the same measure. Additionally, each acute angle is supplementary to each obtuse angle. It’s given that the measure of one of these eight angles is (7x-250)°. It follows that a supplementary angle has measure (180-(7x-250))°, or (-7x+430)°. It’s also given that the sum of the measures of four of the eight angles is k°. It follows that the possible values of k are 4(7x-250); (7x-250)+3(-7x+430); 2(7x-250)+2(-7x+430); 3(7x-250)+(-7x+430); and 4(-7x+430). These values are equivalent to 28x-1,000; -14x+1,040; 360; 14x-320; and -28x+1,720, respectively. It follows that of the given choices, only -14x+1,540 could NOT be equivalent to k, for all values of x.

Choice B is incorrect. This is the sum of three angles with measure (7x-250)° and one angle with measure (-7x+430)°.

Choice C is incorrect. This is the sum of four angles with measure (-7x+430)°.

Choice D is incorrect. This is the sum of two angles with measure (7x-250)° and two angles with measure (-7x+430)°.