An equilateral triangle with side length 9 cm is shown in the diagram, work out the area of the triangle. Give your answer rounded to 1 DP.

Question:-

Find the area of an equilateral triangle with side length = 9cm correct upto one decimal place.

Solution:-

In an equilateral triangle all sides are equal.

Let s = side length = 9 cm

Then, area of equilateral triangle is given as:

A = (√3/4)s²

Putting the value of s here,

A = (√3/4) * (9 cm)²

=> A = (√3/4) * 81 cm²

=> A = √3 * 20.25 cm²

We know that, √3 = 1.732

=> A = 1.732 * 20.25 cm²

=> A = 35.073 cm²

Rounding to one decimal place,

=> A = 35.1 cm²

on friday there were 15 birds

correct answer:

b.(19,-2)