All SAT II Math II Resources
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.
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:
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
A nonagon is a nine-sided polygon.
Nonagon has diagonal with length 10. To the nearest tenth, give the length of one side.
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 ):
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)
Construct the pentagon with diagonal .
We will concern ourselves with finding the length of .
Since , and is isosceles, then
The following diagram is formed:
By the Law of Sines,
Example Question #1 : Trigonometry
In :
Evaluate to the nearest whole unit.
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?
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
A decagon is a ten-sided polygon.
Decagon has diagonal with length 10. To the nearest tenth, give the length of one side.
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 ):
By the Law of Sines,
Example Question #1 : Finding Angles With Trigonometry
In :
Evaluate to the nearest degree.
The figure referenced is below:
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 ?
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.
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,
The trigonometric identity , is an important identity to memorize.
Some other identities that are important to know are:
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