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SAT Math: Geometry

SAT Question of the Day

The SAT question of the day is a Geometry question that tests your knowledge of triangles.

Read the entire question carefully:  The triangle that you are working with is an isosceles triangle.  You know that one of its angles is 74 degrees.

Identify the bottom line:  What must be the measurement of another one of the angles? 

Assess your options:  Use your knowledge of the properties of an isosceles triangle to find the answer. 

Attack the problem:  All isosceles triangles have two sides and two angles that are the same.  Right now you only know one of the angles.  That means that you have two options.  The angle 74 could be used twice:

74 + 74 + x = the 180 degrees in every triangle.

OR The missing angle that you do not know could be used twice: 

74 + y + y = 180

NOTICE and Loop Back:  You were not asked to find what the other angles could be.  You were asked to find what one must be.  Without even figuring out what your variables could be, you know that there are multiple answers.  (You could see that the x variable must end in a 2 and the y variable must end in a 3 in order to get a 0 in the ones digit of 180, or you could see that x must be smaller than y for the equations to balance out. You can also solve for x and y, but that takes time.)  Your options for the missing angles are 74 and x or y and y.   There is no way to answer what the angle must be, because there is no common answer between your two choices.  Look down at your answer choices.  If you answer (A) or (C), you provide the answer to the question what could an angle measurement be?

The correct answer is (E).  You cannot determine the answer.

On sat.collegeboard.org, 37% of the responses were correct.

ACT Question of the Day

The ACT question of the day is an English question that has already been addressed on this blog: click here to see an explanation.

To get help preparing for the SAT, PSAT, or ACT exam, check out the Knowsys College Readiness Program.

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