SAT II Math II : SAT Subject Test in Math II

Study concepts, example questions & explanations for SAT II Math II

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Example Questions

Example Question #1 : Trigonometry

The area of a regular nonagon (nine-sided polygon) is 900. Give its perimeter to the nearest whole number.

Possible Answers:

Correct answer:

Explanation:

A regular nonagon can be divided into eighteen congruent triangles by its nine radii and its nine apothems, each of which is shaped as shown:

 

 Thingy_1

The area of one such triangle is , so the area of the entire nonagon is eighteen times this, or . Since the area is 900,

, or

.

Also,

, or equivalently, , so solve for  in the equation

The perimeter of the nonagon is eighteen times this:

, the correct response.

 

Example Question #451 : Sat Subject Test In Math Ii

nonagon is a nine-sided polygon.

Nonagon  has diagonal  with length 10. To the nearest tenth, give the length of one side.

Possible Answers:

Correct answer:

Explanation:

Construct the nonagon with diagonal .

We will concern ourselves with finding the length of .

Since , and  is isosceles, then  

The following diagram is formed (limiiting ourselves to ):

 Decagon

By the Law of Sines,

Example Question #452 : Sat Subject Test In Math Ii

Give the length of one side of a regular pentagon whose diagonals measure 10 each. (Nearest tenth)

Possible Answers:

Correct answer:

Explanation:

Construct the pentagon with diagonal .

We will concern ourselves with finding the length of .

Since , and  is isosceles, then  

The following diagram is formed:

Pentagon

By the Law of Sines,

Example Question #1 : Trigonometry

In :

Evaluate  to the nearest whole unit.

Possible Answers:

Correct answer:

Explanation:

The Law of Sines states that given two angles of a triangle with measures , and their opposite sides of lengths , respectively,

,

or, equivalently,

.

, whose length is desired, and , whose length is given, are opposite  and , respectively, so, in the sine formula, set , and  in the Law of Sines formula, then solve for :

Example Question #4 : Finding Sides With Trigonometry

Suppose the distance from a student's eyes to the floor is 4 feet.  He stares up at the top of a tree that is 20 feet away, creating a 30 degree angle of elevation. How tall is the tree?

Possible Answers:

Correct answer:

Explanation:

The height of the tree requires using trigonometry to solve.  The distance of the student to the tree , partial height of the tree , and the distance between the student's eyes to the top of the tree will form the right triangle.

The tangent operation will be best used for this scenario, since we have the known distance of the student to the tree, and the partial height of the tree.

Set up an equation to solve for the partial height of the tree.

Multiply by 20 on both sides.

We will need to add this with the height of the student's eyes to the ground to get the height of the tree.

The answer is:  

Example Question #2 : Finding Sides With Trigonometry

decagon is a ten-sided polygon.

Decagon  has diagonal  with length 10. To the nearest tenth, give the length of one side.

Possible Answers:

Correct answer:

Explanation:

Construct the decagon with diagonal .

We will concern ourselves with finding the length of .

Since , and  is isosceles, then  

The following diagram is formed (limiting ourselves to ):

 Decagon

By the Law of Sines,

Example Question #1 : Finding Angles With Trigonometry

In :

Evaluate  to the nearest degree.

Possible Answers:

Correct answer:

Explanation:

The figure referenced is below: 

Triangle z

 

 

By the Law of Cosines, the relationship of the measure of an angle  of a triangle and the three side lengths , and  the sidelength opposite the aforementioned angle, is as follows:

All three side lengths are known, so we are solving for . Setting

, the length of the side opposite the unknown angle;

;

;

and ,

We get the equation

Solving for :

Taking the inverse cosine:

,

the correct response.

Example Question #1 : How To Find Negative Sine

If , what is  if  is between  and ?

Possible Answers:

Correct answer:

Explanation:

Recall that .

Therefore, we are looking for  or .

Now, this has a reference angle of , but it is in the third quadrant. This means that the value will be negative. The value of  is . However, given the quadrant of our angle, it will be .

Example Question #457 : Sat Subject Test In Math Ii

Find the value of  in exact form.

Possible Answers:

Correct answer:

Explanation:

Recall that:

This means that:  

Divide the two terms.

This means that .

The answer is:  

Example Question #1 : Trigonometric Identities

According to the trigonometric identities, 

Possible Answers:

Correct answer:

Explanation:

The trigonometric identity , is an important identity to memorize.

Some other identities that are important to know are:

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