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).

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

For help with the SAT Vocabulary, check out our flashcardsflashcard apps, and iBook activities.