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ACT Math: Triangles

SAT Question of the Day

The SAT question of the day is an Identifying Sentence Errors question that has already been addressed on this blog: click here to see an explanation.

ACT Question of the Day

The ACT question of the day is a math question.  The ACT differs from the SAT in that you must know some trigonometry in order to do well.

Today's question asks you to find the sine of angle A in triangle ABC.  Finding the sine is easy if you remember SohCahToa: Sine = opposite/hypotenuse, Cosine = adjacent/hypotenuse, and Tangent = opposite/adjacent.

The diagram of a triangle shows that angle A is opposite a side that is labeled 24 cm. However, the hypotenuse is not labeled. You could use the Pythagorean theorem to solve for the hypotenuse(A2 + B2 = C2), but there is a faster way to find this value. This is one of three special right triangles that you should have memorized. It is a 7-24-25 triangle. When you are given two sides of this type of triangle, you can always name the third. In this problem you have been given a 7 and a 24, so the hypotenuse must be 25.

Now put what you know together.  The sine of angle A is equal to the opposite side (24) over the hypotenuse (25).  Your answer is the fraction 24/25.

The correct answer is (D).

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