1. 11.2 Areas of Equilateral Triangles

2. Objective:
Students will learn how to:
• Find the area of a equilateral
triangle.
Standards: 10
Students compute areas of polygons, including rectangles,
scalene
triangles, equilateral triangles, rhombi, parallelograms, and
trapezoids.

3. Pencils Down
What is the area of an equilateral Δ?
Area of a Δ?
A = ½ bh
ss
s
60o
30o
2
s
2
3s









2
3
)(
2
1 s
sA
4
32
s
A 

4. Th 11.3
Area of an equilateral ∆
s s
s
A
s


2
3
4

5. Ex:
Find the area of the equilateral Δ shown.
10 cm
4
32
s
A 
4
3102
A
4
3100

2
3.43325 cm

6. Find the area of a yield sign.
A
s


2
3
4

30 3
4
2

900 3
4
 225 3
 389 7.
30in
in2

7. Find the area of the equilateral Δ if the perimeter
of the triangle is 27.
A
s


2
3
4
9 in9 in
9 in
4
392
A
4
381

2
1.35325.20 in

8. 1. SIDE OF 4 IN.
2. SIDE OF 12 IN.
3. PERIMETER OF 36 YARDS.
4. PERIMETER OF 42 FT.
EXTRA CREDIT
FIND THE SIDE WITH AREA OF 9 𝟑
Pop Quiz
Find the Area