 Hi, and welcome to the session. Let us just ask the following question. The question says, a target signal board indicating school ahead is an equated triangle with site A. Find the area of the signal board using heron's formula. If its perimeter is 180 centimeters, what will be the area of the signal board? Before solving this question, we should first be focused with heron's formula. We use this formula for finding the area of a triangle when all its sites are given. This formula states that area of a triangle is equal to square root of into s minus a into s minus b into s minus c, where a, b, and c are the sides of the triangle, the perimeter of the triangle. And this s is equal to a plus b plus c by 2. The knowledge of this formula is a key idea in this question. Now, suppose this is a traffic signal board which is in the shape of an equated triangle. As this is an equated triangle, so let each side of this triangle is equal to a. We have to first find area of this signal board by using heron's formula. Let's first calculate the semi-parimeter of this triangle as each side is equal to a. Therefore, semi-parimeter is equal to a plus a plus a by 2. And this is equal to 3a by 2. From heron's formula, we know that area of a triangle is equal to square root of s into s minus a into s minus b into s minus c. Semi-parimeter that is s is equal to 3a by 2, and all sides are equal to a. So let's now substitute the values of s and the sides in this formula. By substituting the values of s and the sides, we get 3a by 2 into 3a by 2 minus a into 3a by 2 minus a into 3a by 2 minus a. And this is equal to square root of 3a by 2 into a by 2 into a by 2 into a by 2. And this is equal to square root of 3 into a to the power 4 by 60. And this is equal to root 3 into a square by 4. So area of the traffic signal board is equal to root 3 by 4 into a square. Find the area of the signal board if its perimeter is 180 centimeters. Perimeter means sum of all the sides as the triangle is equilateral. Therefore, its perimeter is equal to a plus a plus a. And this a plus a plus a is equal to 180 centimeters. Now this implies 3a is equal to 180 centimeters. This implies a is equal to 60 centimeters. So now we have got the value of a. So by substituting value of a in this, we get area of traffic signal board as p by 4 into 60 centimeters whole square. And this is equal to root 3 by 4 into 3600 centimeters square. And this is equal to 900 into root 3 centimeters square. Hence the required answers are root 3 by 4 a square and 900 into root 3 centimeters square. This completes the session. Bye and take care.