ISEE Upper Level Quantitative : Right Triangles

Study concepts, example questions & explanations for ISEE Upper Level Quantitative

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Example Questions

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Example Question #1 :Right Triangles

What is the hypotenuse of a right triangle with sides 5 and 8?

Possible Answers:

12

√89

5√4

15

Correct answer:

√89

Explanation:

Because this is a right triangle, we can use the Pythagorean Theorem which saysa2+b2=c2, or the squares of the two sides of a right triangle must equal the square of the hypotenuse. Here we havea= 5 andb= 8.

a2+b2=c2

52+ 82=c2

25 + 64 =c2

89 =c2

c= √89

Example Question #2 :Right Triangles

Which is the greater quantity?

(a) The hypotenuse of aright triangle with a leg of length 20

(b) The hypotenuse of a right triangle with legs of length 19 and 21

Possible Answers:

It is impossible to tell from the information given

(b) is greater

(a) is greater

(a) and (b) are equal

Correct answer:

(b) is greater

Explanation:

The hypotenuses of the triangles measure as follows:

(a)

(b)

, so, making (b) the greater quantity

Example Question #3 :Right Triangles

Which is the greater quantity?

(a) The hypotenuse of a right triangle with legsand.

(b) The hypotenuse of a right triangle with legsand.

Possible Answers:

(a) is greater.

It is impossible to tell from the information given.

(a) and (b) are equal.

(b) is greater.

Correct answer:

(a) is greater.

Explanation:

The hypotenuses of the triangles measure as follows:

(a)

(b)

, so, making (a) the greater quantity.

Example Question #4 :Right Triangles

A right triangle has a legfeet long and a hypotenusefeet long. Which is the greater quantity?

(a) The length of the second leg of the triangle

(b) 60 inches

Possible Answers:

(a) is greater.

It is impossible to tell from the information given.

(b) is greater.

(a) and (b) are equal.

Correct answer:

(a) is greater.

Explanation:

The length of the second leg can be calculated using the Pythagorean Theorem. Set:

The second leg therefore measuresinches.

Example Question #5 :Right Triangles

What is the hypotenuse of a right triangle with sides 9 inches and 12 inches?

Possible Answers:

Correct answer:

Explanation:

Since we're dealing with right triangles, we can use the Pythagorean Theorem (). In this formula, a and b are the sides, while c is the hypotenuse. The hypotenuse of a right triangle is the longest side and the side that is opposite the right angle. Now, we can plug into our formula, which looks like this:We simplify and get. At this point, isolate c. This means taking the square root of both sides so that your answer is 15in.

Example Question #6 :Right Triangles

Right_triangle

The perimeter of a regular pentagon is 75% of that of the triangle in the above diagram. Which is the greater quantity?

(A) The length of one side of the pentagon

(B) One and one-half feet

Possible Answers:

(A) is greater

(A) and (B) are equal

It is impossible to determine which is greater from the information given

(B) is greater

Correct answer:

(B) is greater

Explanation:

By the Pythagorean Theorem, the hypotenuse of the right triangle is

inches, making its perimeter

inches.

The pentagon in question has sides of length 75% of 112, or

.

Since a pentagon has five sides of equal length, each side will have measure

inches.

One and a half feet are equivalent toinches, so (B) is the greater quantity.

Example Question #7 :Right Triangles

Right_triangle

The track at Gauss High School is unusual in that it is shaped like a right triangle, as shown above.

Cary decides to get some exercise by running from point A to point B, then running half of the distance from point B to point C.

Which is the greater quantity?

(A) The distance Cary runs

(B) One-fourth of a mile

Possible Answers:

(A) is greater

(B) is greater

It is impossible to determine which is greater from the information given

(A) and (B) are equal

Correct answer:

(B) is greater

Explanation:

By the Pythagorean Theorem, the distance from B to C is

feet

Cary runs

feet

Since 5,280 feet make a mile, one-fourth of a mile is equal to

feet.

(B) is greater

Example Question #8 :Right Triangles

Right_triangle

Give the length of the hypotenuse of the above right triangle in terms of.

Possible Answers:

Correct answer:

Explanation:

If we letbe the length of the hypotenuse, then by the Pythagorean theorem,

Example Question #9 :Right Triangles

In Square.is the midpoint of,is the midpoint of, andis the midpoint of. Construct the line segmentsand.

Which is the greater quantity?

(a)

(b)

Possible Answers:

(a) is the greater quantity

(b) is the greater quantity

(a) and (b) are equal

It cannot be determined which of (a) and (b) is greater

Correct answer:

(b) is the greater quantity

Explanation:

The figure referenced is below:
Square x

For the sake of simplicity, assume that the square has sides of length 4. The following reasoning is independent of the actual lengths, and the reason for choosing 4 will become apparent in the explanation.

andare midpoints of their respective sides, so, makingthe hypotenuse of a triangle with legs of length 2 and 2. Therefore,

.

Also,, and sinceis the midpoint of,., makingthe hypotenuse of a triangle with legs of length 1 and 4. Therefore,

, so

Example Question #10 :Right Triangles

Untitled

Figure NOT drawn to scale.

In the above figure,is a right angle.

What is the length of?

Possible Answers:

Correct answer:

Explanation:

The altitude of a right triangle from the vertex of its right angle divides the triangle into two smaller triangles each similar to the larger triangle. In particular,

.

Their corresponding sides are in proportion, so, setting the ratios of the hypotenuses to the short legs equal to each other,

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