Intermediate Geometry : Acute / Obtuse Triangles

Study concepts, example questions & explanations for Intermediate Geometry

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Example Questions

Example Question #145 : Triangles

A triangle is placed so that it shares a base with a parallelogram.

3

If the height of the triangle is one-third that of the parallelogram, find the area of the shaded region.

Possible Answers:

Correct answer:

Explanation:

13

In order to find the area of the shaded region, we will need to find the areas of the triangle and of the parallelogram.

First, recall how to find the area of a parallelogram.

Next, recall how to find the area of a triangle.

Now, find the height of the triangle.

Plug this value in to find the area of the triangle.

Subtract the two areas to find the area of the shaded region.

Example Question #146 : Triangles

A triangle is placed in a parallelogram so that they share a base.

4

If the height of the triangle is half that of the parallelogram, find the area of the shaded region.

Possible Answers:

Correct answer:

Explanation:

13

In order to find the area of the shaded region, we will need to find the areas of the triangle and of the parallelogram.

First, recall how to find the area of a parallelogram.

Next, recall how to find the area of a triangle.

Now, find the height of the triangle.

Plug this value in to find the area of the triangle.

Subtract the two areas to find the area of the shaded region.

Example Question #591 : Plane Geometry

A triangle is placed in a parallelogram so that they share a base.

5

If the height of the triangle is half the height of the parallelogram, find the area of the shaded region.

Possible Answers:

Correct answer:

Explanation:

13

In order to find the area of the shaded region, we will need to find the areas of the triangle and of the parallelogram.

First, recall how to find the area of a parallelogram.

Next, recall how to find the area of a triangle.

Now, find the height of the triangle.

Plug this value in to find the area of the triangle.

Subtract the two areas to find the area of the shaded region.

Example Question #592 : Plane Geometry

A triangle is placed in a parallelogram so that they share a base. 

6

If the height of the triangle is half the height of the parallelogram, find the area of the shaded region.

Possible Answers:

Correct answer:

Explanation:

13

In order to find the area of the shaded region, we will need to find the areas of the triangle and of the parallelogram.

First, recall how to find the area of a parallelogram.

Next, recall how to find the area of a triangle.

Now, find the height of the triangle.

Plug this value in to find the area of the triangle.

Subtract the two areas to find the area of the shaded region.

Example Question #591 : Intermediate Geometry

A triangle is placed in a parallelogram so that they share a base.

7

If the height of the triangle is one-fifth that of the parallelogram, find the area of the shaded region.

Possible Answers:

Correct answer:

Explanation:

13

In order to find the area of the shaded region, we will need to find the areas of the triangle and of the parallelogram.

First, recall how to find the area of a parallelogram.

Next, recall how to find the area of a triangle.

Now, find the height of the triangle.

Plug this value in to find the area of the triangle.

Subtract the two areas to find the area of the shaded region.

Example Question #593 : Plane Geometry

A triangle is placed in a parallelogram so that they share a base.

8

If the height of the triangle is half that of the parallelogram, find the area of the shaded region.

Possible Answers:

Correct answer:

Explanation:

13

In order to find the area of the shaded region, we will need to find the areas of the triangle and of the parallelogram.

First, recall how to find the area of a parallelogram.

Next, recall how to find the area of a triangle.

Now, find the height of the triangle.

Plug this value in to find the area of the triangle.

Subtract the two areas to find the area of the shaded region.

Example Question #155 : Triangles

A triangle is placed in a parallelogram so that they share a base.

10

If the height of the triangle is one-ninth that of the parallelogram, find the area of the shaded region.

Possible Answers:

Correct answer:

Explanation:

13

In order to find the area of the shaded region, we will need to find the areas of the triangle and of the parallelogram.

First, recall how to find the area of a parallelogram.

Next, recall how to find the area of a triangle.

Now, find the height of the triangle.

Plug this value in to find the area of the triangle.

Subtract the two areas to find the area of the shaded region.

Example Question #156 : Triangles

A triangle is placed in a parallelogram so that they share a base.

11

If the height of the triangle is half that of the parallelogram, find the area of the shaded region.

Possible Answers:

Correct answer:

Explanation:

13

In order to find the area of the shaded region, we will need to find the areas of the triangle and of the parallelogram.

First, recall how to find the area of a parallelogram.

Next, recall how to find the area of a triangle.

Now, find the height of the triangle.

Plug this value in to find the area of the triangle.

Subtract the two areas to find the area of the shaded region.

Example Question #157 : Triangles

A triangle is placed in a parallelogram so that they share a base.

12

If the height of the triangle is half that of the parallelogram, find the area of the shaded region.

Possible Answers:

Correct answer:

Explanation:

13

In order to find the area of the shaded region, we will need to find the areas of the triangle and of the parallelogram.

First, recall how to find the area of a parallelogram.

Next, recall how to find the area of a triangle.

Now, find the height of the triangle.

Plug this value in to find the area of the triangle.

Subtract the two areas to find the area of the shaded region.

Example Question #1 : How To Find The Length Of The Side Of An Acute / Obtuse Triangle

In ΔABC: a = 10, c = 15, and B = 50°.

Find b (to the nearest tenth).

Possible Answers:

9.7

14.3

12.1

11.9

11.5

Correct answer:

11.5

Explanation:

This problem requires us to use either the Law of Sines or the Law of Cosines. To figure out which one we should use, let's write down all the information we have in this format:

A = ?          a = 10

B = 50°       b = ?

C = ?          c = 15

Now we can easily see that we do not have any complete pairs (such as A and a, or B and b) but we do have one term from each pair (a, B, and c). This tells us that we should use the Law of Cosines. (We use the Law of Sines when we have one complete pair, such as B and b).

Law of Cosines:


Since we are solving for b, let's use the second version of the Law of Cosines.
This gives us:



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