SAT II Math II : 2-Dimensional Geometry

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

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Example Questions

Example Question #3 : Diameter, Radius, And Circumference

Determine the radius of a circle if the circumference is .

Possible Answers:

Correct answer:

Explanation:

Write the formula for the circumference of a circle.

Substitute the circumference.

Multiply by  on both sides to isolate .

The radius is:  

Example Question #2 : Diameter, Radius, And Circumference

Determine the diameter if the radius of a circle is .

Possible Answers:

Correct answer:

Explanation:

The diameter is double the radius.  Multiply the radius by two.

The answer is:  

Example Question #3 : Diameter, Radius, And Circumference

Determine the circumference of a circle with a radius of .

Possible Answers:

Correct answer:

Explanation:

The circumference of a circle is:  

Substitute the radius.

The answer is:  

Example Question #41 : 2 Dimensional Geometry

Triangle

Note: figure NOT drawn to scale.

Refer to the triangle in the above diagram. 

Evaluate . Round to the nearest tenth, if applicable.

Possible Answers:

Correct answer:

Explanation:

By the Law of Cosines,

Substitute :

Example Question #2 : Finding Sides

In triangle  and .

Which of the following statements is true about the lengths of the sides of  ?

Possible Answers:

Correct answer:

Explanation:

In a triangle, the shortest side is opposite the angle of least measure; the longest side is opposite the angle of greatest measure. Therefore, if we order the angles, we can order their opposite sides similarly. 

Since the measures of the three interior angles of a triangle must total 

Since

,

we can order the lengths of their opposite sides the same way:

.

Example Question #1 : Finding Sides

Triangle

Note: figure NOT drawn to scale.

Refer to the above diagram.

.

Which of the following expressions is equal to  ?

Possible Answers:

Correct answer:

Explanation:

By the Law of Sines,

.

Substitute , and :

 

Solve for :

Example Question #1 : Finding Sides

Which of the following describes a triangle with sides of length 9 feet, 3 yards, and 90 inches?

Possible Answers:

The triangle is obtuse and scalene.

The triangle is acute and isosceles, but not equilateral.

The triangle is acute and equilateral.

The triangle is acute and scalene.

The triangle is obtuse and isosceles, but not equilateral.

Correct answer:

The triangle is acute and isosceles, but not equilateral.

Explanation:

One yard is equal to three feet; One foot is equal to twelve inches. Therefore, 9 feet is equal to  inches, and 3 yards is equal to  inches. The triangle has sides of measure 90, 108, 108.

We compare the squares of the sides.

The sum of the squares of the two smaller sidelengths exceeds that of the third, so the triangle is acute.

The correct response is acute and isosceles.

Example Question #2 : Finding Sides

Triangle

Note: figure NOT drawn to scale.

Refer to the above diagram.

.

Which of the following expressions is equal to  ?

Possible Answers:

Correct answer:

Explanation:

By the Law of Sines,

.

Substitute , and :

We can solve for :

Example Question #6 : Finding Sides

Triangle

Note: figure NOT drawn to scale.

Refer to the triangle in the above diagram.

.

Evaluate .

Possible Answers:

Correct answer:

Explanation:

By the Law of Sines,

Substitute  and solve for :

Example Question #2 : Finding Sides

Decagon

The above figure is a regular decagon. Evaluate  to the nearest tenth.

Possible Answers:

Correct answer:

Explanation:

Two sides of the triangle formed measure 6 each; the included angle is one angle of the regular decagon, which measures

.

Since we know two sides and the included angle of the triangle in the diagram, we can apply the Law of Cosines, 

with  and :

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