SAT II Math I : SAT Subject Test in Math I

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

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Example Questions

Example Question #491 : Sat Subject Test In Math I

Regular Hexagon  has perimeter 120.  has  as its midpoint; segment  is drawn. To the nearest tenth, give the length of .

Possible Answers:

Correct answer:

Explanation:

The perimeter of the regular hexagon is 80, so each side measures one sixth of this, or 20. Also, since  is the midpoint of 

Also, each interior angle of a regular hexagon measures .

Below is the hexagon in question, with  indicated and  constructed; all relevant measures are marked. 

Hexagon

A triangle  is formed with , and included angle measure . The length of the remaining side can be calculated using the Law of Cosines: 

where  and  are the lengths of two sides,  is the measure of their included angle, and  is the length of the third side. 

Setting , and , substitute and evaluate :

;

Taking the square root of both sides:

,

the correct choice.

Example Question #51 : Geometry

Regular Pentagon  has perimeter 80.  has  as its midpoint; segment  is drawn. To the nearest tenth, give the length of .

Possible Answers:

Correct answer:

Explanation:

The perimeter of the regular pentagon is 80, so each side measures one fifth of this, or 16. Also, since  is the midpoint of 

Also, each interior angle of a regular pentagon measures .

 

Below is the pentagon in question, with  indicated and  constructed; all relevant measures are marked. 

Pentagon 2

A triangle  is formed with , and included angle measure . The length of the remaining side can be calculated using the law of cosines: 

where  and  are the lengths of two sides,  is the measure of their included angle, and  is the length of the third side. 

Setting , and , substitute and evaluate :

;

Taking the square root of both sides:

,

the correct choice.

Example Question #21 : Finding Sides

If the two legs of a right triangle are  and , find the third side. 

Possible Answers:

Correct answer:

Explanation:

Step 1: Recall the formula used to find the missing side(s) of a right triangle...

Step 2: Identify the legs and the hypotenuse in the formula...

 are the legs, and  is the hypotenuse.

Step 3: Plug in the values of a and b given in the question...

Step 3: A special rule about all triangles...

For any triangle, the measurements of any of the sides CANNOT BE zero.

So, the missing side is , or 

Example Question #493 : Sat Subject Test In Math I

Regular Pentagon  has perimeter 80.  and  have  and as midpoints, respectively; segment  is drawn. Give the length of  to the nearest tenth.

Possible Answers:

Correct answer:

Explanation:

The perimeter of the regular pentagon is 80, so each side measures one fifth of this, or 16. Since  is the midpoint of 

Similarly, .

Also, each interior angle of a regular pentagon measures .

Below is the pentagon with the midpoints  and , and with  constructed. Note that perpendiculars have been drawn to  from  and , with feet at points  and , respectively.

Pentagon 2

 is a rectangle, so .

, or 

. Substituting:

For the same reason, 

.

Adding the segment lengths:

Rond answer to the nearest tenth.

 

 

Example Question #61 : Geometry

Regular Pentagon  has a perimeter of eighty. 

Give the length of diagonal  to the nearest tenth.

Possible Answers:

Correct answer:

Explanation:

The perimeter of the regular pentagon is 80, so each side measures one fifth of this, or 16. Also, each interior angle of a regular pentagon measures .

The pentagon, along with diagonal , is shown below:

Pentagon 2

A triangle  is formed with , and included angle measure . The length of the remaining side can be calculated using the law of cosines: 

,

where  and  are the lengths of two sides,  the measure of their included angle, and  the length of the side opposite that angle.

Setting , and , substitute and evaluate :

Taking the square root of both sides:

,

the correct choice.

Example Question #141 : Quadrilaterals

 is rhombus with side lengths in meters.  and . What is the length, in meters, of ?

Rhombus_1

Possible Answers:

30

24

15

5

12

Correct answer:

24

Explanation:

A rhombus is a quadrilateral with four sides of equal length. Rhombuses have diagonals that bisect each other at right angles.

Rhombus_2

Thus, we can consider the right triangle  to find the length of diagonal . From the given information, each of the sides of the rhombus measures  meters and .

Because the diagonals bisect each other, we know:

Using the Pythagorean theorem,

Example Question #1 : Finding Angles

What angle do the minute and hour hands of a clock form at 4:45?

Possible Answers:

Correct answer:

Explanation:

There are twelve numbers on a clock; from one to the next, a hand rotates . At 4:45, the minute hand is exactly on the "9" - that is, at the . The hour hand is three-fourths of the way from the "4" to the "5" - that is, on the  position. Therefore, the difference is the angle they make:

Example Question #2 : Finding Angles

What angle do the minute and hour hands of a clock form at 8:50?

Possible Answers:

Correct answer:

Explanation:

There are twelve numbers on a clock; from one to the next, a hand rotates . At 8:50, the minute hand is exactly on the "10" - that is, on the  position. The hour hand is five-sixth of the way from the "8" to the "9" - that is, on the  position. Therefore, the difference is the angle they make:

.

Example Question #491 : Sat Subject Test In Math I

Hexagon

Note: Figure NOT drawn to scale.

The above hexagon is regular. What is ?

Possible Answers:

Correct answer:

Explanation:

Two of the angles of the quadrilateral formed are angles of a regular hexagon, so each measures

.

The four angles of the quadrilateral are . Their sum is , so we can set up, and solve for  in, the equation:

Example Question #1 : Finding Angles

Can a triangle have a set of angles that are  and  degrees?

Possible Answers:

No

Yes

Correct answer:

No

Explanation:

A triangle's angles must add up to  degrees.  

The angles given add up to 181,

.  

That means that this cannot be an actual triangle.

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