Lesson Example Discussion Quiz: Class Homework |
Step-4 |
Title: Median of triangle |
Grade: 7-a Lesson: S3-L2 |
Explanation: |
Step | Type | Explanation | Answer |
---|---|---|---|
1 |
Problem |
Obtain the value of CD, which is the median of the traingle ABC, if AC = 6, CB = 13 and AB = 15. |
|
2 |
Given |
In a triangle ACB, CD is the median, and sides AC = 6, CB = 13, AB = 15. |
|
3 |
Formula: |
The median of the triangle is given by |
\$CD = \sqrt{\frac{2(BC) ^2 + 2(AC) ^2 - (AB) ^2}{4}} \$ |
4 |
Step |
Substitute the values. |
\$\Rightarrow CD = \sqrt{\frac{2(13) ^2 + 2(6) ^2 - (15) ^2}{4}}\$ |
5 |
Step |
Calculate the exponents. |
\$\Rightarrow CD = \sqrt{\frac{2(169) + 2(36) - 225}{4}}\$ |
6 |
Step |
Multiply. |
\$\Rightarrow CD = \sqrt{\frac{338 + 72 - 225}{4}}\$ |
7 |
Step |
Add and subtract. |
\$\Rightarrow CD = \sqrt{\frac{185}{4}}\$ |
8 |
Step |
Simplify. |
\$Rightarrow CD = \frac{\sqrt{185}}{2}\$ |
9 |
Step |
Answer |
The value of the median CD of triangle ABC = \$\frac{\sqrt{185}}{2}\$. |
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