SAT Math : Triangles

Study concepts, example questions & explanations for SAT Math

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Example Questions

Example Question #15 :How To Find The Area Of A Right Triangle

The ratio for the side lengths of a right triangle is 3:4:5. If the perimeter is 48, what is the area of the triangle?

Possible Answers:

50

48

240

108

96

Correct answer:

96

Explanation:

We can model the side lengths of the triangle as 3x, 4x, and 5x. We know that perimeter is 3x+4x+5x=48, which implies that x=4. This tells us that the legs of the right triangle are 3x=12 and 4x=16, therefore the area is A=1/2 bh=(1/2)(12)(16)=96.

Example Question #1 :How To Find The Area Of A Right Triangle

The length of one leg of an equilateral triangle is 6. What is the area of the triangle?

Possible Answers:

Correct answer:

Explanation:

The base is equal to 6.

The height of an quilateral triangle is equal to, whereis the length of the base.

Example Question #11 :Triangles

Right triangle

Figure NOT drawn to scale.

is a right triangle with altitude. What percent ofis shaded in?

Choose the closest answer.

Possible Answers:

Correct answer:

Explanation:

The altitude of a right triangle from the vertex of its right angle - which, here, is- divides the triangle into two triangles similar to each other and to the large triangle. From the Pythagorean Theorem, the hypotenuse ofhas length

.

The similarity ratio oftois the ratio of the lengths of the hypotenuses:

The ratio of the areas of two similar triangles is the square of their similarity ratio, which here is

因此,the area ofis

the overall area of. This makesthe closest response.

Example Question #31 :Plane Geometry

The perimeter of a right triangle is 40 units. If the lengths of the sides are,, andunits, then what is the area of the triangle?

Possible Answers:

Correct answer:

Explanation:

Because the perimeter is equal to the sum of the lengths of the three sides of a triangle, we can add the three expressions for the lengths and set them equal to 40.

Perimeter:

Simplify the x terms.

Simplify the constants.

Subtract 8 from both sides.

Divide by 4

One side is 8.

The second side is

.

The third side is

.

Thus, the sides of the triangle are 8, 15, and 17.

The question asks us for the area of the triangle, which is given by the formula (1/2)bh. We are told it is a right triangle, so we can use one of the legs as the base, and the other leg as the height, since the legs will intersect at right angles. The legs of the right triangle must be the smallest sides (the longest must be the hypotenuse), which in this case are 8 and 15. So, let's assume that 8 is the base and 15 is the height.

The area of a triangle is (1/2)bh. We can substitute 8 and 15 for b and h.

.

The answer is 60 units squared.

Example Question #13 :Triangles

The vertices of a right triangle on the coordinate axes are at the origin,, and. Give the area of the triangle.

Possible Answers:

Correct answer:

Explanation:

The triangle in question can be drawn as the following:

Right triangle 8

The lengths of the legs of the triangle are 12, the distance from the origin to, and 8, the distance from the origin to. The area of a right triangle is equal to half the product of the lengths of the legs, so setin the formula:

Example Question #14 :Triangles

Three points in the xy-coordinate system form a triangle.

The points are.

What is the perimeter of the triangle?

Possible Answers:

9 + \sqrt{71}

9 + \sqrt{41}

9 + \sqrt{26}

Correct answer:

9 + \sqrt{41}

Explanation:

Drawing points gives sides of a right triangle of 4, 5, and an unknown hypotenuse.

Using the pythagorean theorem we find that the hypotenuse is\sqrt{41}.

Example Question #15 :Triangles

Triangle

Based on the information given above, what is the perimeter of triangle ABC?

Possible Answers:

Correct answer:

Explanation:

Triangle-solution

Consult the diagram above while reading the solution. Because of what we know about supplementary angles, we can fill in the inner values of the triangle. Angles A and B can be found by the following reductions:

A + 120 = 180; A = 60

B + 150 = 180; B = 30

Since we know A + B + C = 180 and have the values of A and B, we know:

60 + 30 + C = 180; C = 90

This gives us a 30:60:90 triangle. Now, since 17.5 is across from the 30° angle, we know that the other two sides will have to be √3 and 2 times 17.5; therefore, our perimeter will be as follows:

Example Question #16 :Triangles

Right triangle 7

Give the perimeter of the provided triangle.

Possible Answers:

Correct answer:

Explanation:

The figure shows a right triangle. The acute angles of a right triangle have measures whose sum is, so

Substitutingfor:

This makesa 45-45-90 triangle.

By the 45-45-90 Triangle Theorem, legsare of the same length, so

.

Also by the 45-45-90 Triangle Theorem, the length of hypotenuseis equal to that of legmultiplied by. Therefore,

.

The perimeter of the triangle is

Example Question #17 :Triangles

Right triangle 7

What is the perimeter of the triangle above?

Possible Answers:

Correct answer:

Explanation:

The figure shows a right triangle. The acute angles of a right triangle have measures whose sum is, so

Substitutingfor:

This makesa 45-45-90 triangle. By the 45-45-90 Triangle Theorem, the length of legis equal to that of hypotenuse, the length of which is 12, divided by. Therefore,

Rationalize the denominator by multiplying both halves of the fraction by:

By the same reasoning,.

The perimeter of the triangle is

Example Question #1 :How To Find The Length Of The Hypotenuse Of A Right Triangle : Pythagorean Theorem

Trig_id

If, how long is side?

Possible Answers:

Not enough information to solve

Correct answer:

Explanation:

This problem is solved using the Pythagorean theorem. In this formulaare the legs of the right triangle whileis the hypotenuse.

Using the labels of our triangle we have:

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