年代AT Math : How to find the length of the hypotenuse of a right triangle : Pythagorean Theorem

年代tudy concepts, example questions & explanations for SAT Math

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Example Questions

Example Question #12 :Apply The Pythagorean Theorem To Find The Distance Between Two Points In A Coordinate System: Ccss.Math.Content.8.G.B.8

Jim leaves his home and walks 10 minutes due west and 5 minutes due south. If Jim could walk a straight line from his current position back to his house, how far, in minutes, is Jim from home?

Possible Answers:

√5

6√6

5√5

√10

Correct answer:

5√5

Explanation:

By using Pythagorean Theorem, we can solve for the distance “as the crow flies” from Jim to his home:

102+ 52=x2

100 + 25 =x2

√125 = x,但我们仍然需要因子r的平方oot

√125 = √25*5, and since the √25 = 5, we can move that outside of the radical, so

5√5=x

Example Question #111 :Act Math

A square enclosure has a total area of 3,600 square feet. What is the length, in feet, of a diagonal across the field rounded to the nearest whole number?

Possible Answers:

60

85

100

95

75

Correct answer:

85

Explanation:

我n order to find the length of the diagonal accross a square, we must first find the lengths of the individual sides.

The area of a square is found by multiply the lengths of 2 sides of a square by itself.

年代o, the square root of 3,600 comes out to 60 ft.

The diagonal of a square can be found by treating it like a right triangle, and so, we can use the pythagorean theorem for a right triangle.

602+ 602= C2

the square root of 7,200 is 84.8, which can be rounded to 85

Example Question #31 :How To Find The Length Of The Hypotenuse Of A Right Triangle : Pythagorean Theorem

Triangle

我f the length of CB is 6 and the angle C measures 45º, what is the length of AC in the given right triangle?

Possible Answers:

6

6√2

72

12√2

9

Correct answer:

6√2

Explanation:

Pythagorean Theorum

AB2+ BC2= AC2

我f C is 45º then A is 45º, therefore AB = BC

AB2+ BC2= AC2

62+ 62= AC2

2*62= AC2

AC = √(2*62) = 6√2

Example Question #13 :Apply The Pythagorean Theorem To Find The Distance Between Two Points In A Coordinate System: Ccss.Math.Content.8.G.B.8

You leave on a road trip driving due North from Savannah, Georgia, at 8am. You drive for 5 hours at 60mph and then head due East for 2 hours at 50mph. After those 7 hours, how far are you Northeast from Savannah as the crow flies (in miles)?

Possible Answers:

Correct answer:

Explanation:

Distance = hours * mph

North Distance = 5 hours * 60 mph = 300 miles

East Distance = 2 hours * 50 mph = 100 miles

Use Pythagorean Theorem to determine Northeast Distance

3002 +1002=NE2

90000 + 10000 = 100000 = NE2

NE = √100000

Example Question #113 :Act Math

A square garden has an area of 49 ft2. To the nearest foot, what is the diagonal distance across the garden?

Possible Answers:

7

9

8

10

11

Correct answer:

10

Explanation:

因为花园广场,双方是方程l to the square root of the area, making each side 7 feet. Then, using the Pythagorean Theorem, set up the equation 72+ 72= the length of the diagonal squared. The length of the diagonal is the square root of 98, which is closest to 10.

Example Question #51 :Triangles

A man at the top of a lighthouse is watching birds through a telescope. He spots a pelican 5 miles due north of the lighthouse. The pelican flies due west for 12 miles before resting on a buoy. What is the distance, in miles, from the pelican's current resting spot to the lighthouse?

Possible Answers:

Correct answer:

Explanation:

We look at the 3 points of interest: the lighthouse, where the pelican started, and where the pelican ended. We can see that if we connect these 3 points with lines, they form a right triangle. (From due north, flying exactly west creates a 90 degree angle.) The three sides of the triangle are 5 miles, 13 miles and an unknown distance. Using the Pythagorean Theorem we get:

Example Question #14 :Apply The Pythagorean Theorem To Find The Distance Between Two Points In A Coordinate System: Ccss.Math.Content.8.G.B.8

An airplane is 8 miles west and 15 miles south of its destination. Approximately how far is the plane from its destination, in miles?

Possible Answers:

Correct answer:

Explanation:

A right triangle can be drawn between the airplane and its destination.

Destination

15 milesAct_math_170_01Airplane

8 miles

We can solve for the hypotenuse, x, of the triangle:

82+ 152= x2

64 + 225 = x2

289 = x2

x = 17 miles

Example Question #82 :Plane Geometry

An 8-foot-tall tree is perpendicular to the ground and casts a 6-foot shadow. What is the distance, to the nearest foot, from the top of the tree to the end of the shadow?

Possible Answers:

\dpi{100} \small 10

\dpi{100} \small 8

\dpi{100} \small 6

\dpi{100} \small 5

\dpi{100} \small 4

Correct answer:

\dpi{100} \small 10

Explanation:

我n order to find the distance from the top of the tree to the end of the shadow, draw a right triangle with the height(tree) labeled as 8 and base(shadow) labeled as 6:

年代creen_shot_2013-08-16_at_12.34.40_am

From this diagram, you can see that the distance being asked for is the hypotenuse. From here, you can either use the Pythagorean Theorem:

\dpi{100} \small a^{2}+b^{2}=c^{2}

or you can notice that this is simililar to a 3-4-5 triangle. Since the lengths are just increased by a factor of 2, the hypotenuse that is normally 5 would be 10.

Example Question #81 :Plane Geometry

年代creen_shot_2013-03-18_at_10.21.29_pm

我n the figure above,is a square andis three times the length of. What is the area of?

Possible Answers:

Correct answer:

Explanation:

Assigning the length ofEDthe value ofx, the value ofAEwill be 3x. That makes the entire sideADequal to 4x. Since the figure is a square, all four sides will be equal to 4x. Also, since the figure is a square, then angleAof triangleABE是一个直角. That gives triangleABEsides of 3x, 4xand 10. Using the Pythagorean theorem:

(3x)2+ (4x)2= 102

9x2+ 16x2= 100

25x2= 100

x2= 4

x= 2

Withx= 2, each side of the square is 4x, or 8. The area of a square is length times width. In this case, that's 8 * 8, which is 64.

Example Question #81 :Right Triangles

1

The hypotenuse is the diameter of the circle. Find the area of the circle above.

Possible Answers:

6.75\pi

6.25\pi

5\pi

6.5\pi

5.5\pi

Correct answer:

6.25\pi

Explanation:

Using the Pythagorean Theorem, we can find the length of the hypotenuse:

3^{2}+4^{2}=5^{2}.

Therefore the hypotenuse has length 5.

The area of the circle is\pi r^{2}=\pi \cdot 2.5^{2}=6.25\pi

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