Lesson Example Discussion Quiz: Class Homework |
Step-5 |
Title: Area of triangle |
Grade: 7-a Lesson: S4-L2 |
Explanation: |
| Step | Type | Explanation | Answer |
|---|---|---|---|
1 |
Problem |
Find the area of a triangle whose length of each side is 7 inches, 8 inches and 9 inches. |
|
2 |
Step |
To solve this problem, we can use Heron’s formula. Let’s denote the side lengths as a, b, and c. |
|
3 |
Given |
a = 7 inches , b = 8 inches and c = 9 inches |
|
4 |
Formula: |
The area of triangle is given by |
\$A = sqrt(s times (s - a) times (s - b) times (s - c))\$ |
5 |
Formula: |
where s is the semi-perimeter of the triangle is given by |
\$s = (a + b + c) / 2 \$ |
6 |
Step |
Substitute a = 7 ,b = 8 and c = 9 in semi-perimeter formula |
\$s = (7 + 8 + 9) / 2 \$ |
7 |
Step |
After simplification |
s= 12 inches |
8 |
Step |
Now Substitute the values in the area formula |
\$A = sqrt(12 times (12 - 7) times (12 - 8) times (12- 9))\$ |
9 |
Step |
After simplification |
\$A = sqrt(12 times 5 times 4 times 3)\$ |
10 |
Step |
After simplification |
\$A = sqrt(720)\$ |
11 |
Step |
After simplification |
\$A = 26.83 Inches^2\$ |
12 |
Step |
Answer |
The area of the triangle is \$A = 26.83 Inches^2\$ |
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