welcome to math with mr. J in this video I am going to cover how to calculate the area of a triangle and remember area is the amount of space a two-dimensional or flat shape takes up our formula for finding area of triangles is at the top of your screen BH / - and that means base times the height divided by 2 and that's going to give us the area of the triangles on your screen or any triangle that you are finding the area of so like I just mentioned you have some problems on your screen and you have four of them that we are going to work through together so let's hop right in to number one so for number one here the first thing we want to do is write out our formula for the area of the triangle so area equals base times height divided by two now whenever you have two letters right next to each other in a math problem or in an algebra problem that means multiplication okay again two letters right next to each other that means B times H base times height so now under our formula we're going to plug in our base and height so our base of five inches down here this is the base of our triangle so five times the height write that 12 inches so I plug in the 12 and we divide that by two and I'll tell you why at the end of this problem why we divide by two so now it's time to solve so we know 5 times 12 is 60 and now we need to do 60 divided by 2 to get to our answer and notice we have 60 divided by 2 written as a fraction there let's find a fraction is division so that just means 60 divided by 2 which gets us to 30 now we need to put our unit of measure which is inches and we put a two up here and we read that as area equals 30 square inches and we make that a square unit because they're our square inches that cover that triangle to show how much space that figure takes up so area equals 30 square inches now let's go back to why we divide by two so we have a triangle here I'm going to draw some imaginary lines to make this a rectangle slash parallelogram so in order to find the area of that parallelogram or rectangle we would do 5 times 12 the base times the height or length times width and that would get us 60 but this triangle is exactly half of that rectangle or half of that parallelogram so we divide by 2 to give us the area of the triangle or half of that rectangle or parallelogram so let's go to number 2 here and we start by writing out our formula area equals base times height divided by 2 now we plug in area equals base is 14 meters here times the height of 5 meters we do not need the 10 or the 7 and then we need to divide by 2 so area equals well 14 times 5 is 70 and we need to divide 70 by 2 to get our area so area equals 35 meters squared and again we use square units because there are 35 square meters one by one meter squares that however that triangle or fill that area or space so for number three let's start by writing out our formula it's always good habit just to start by writing out the formula so we have area equals base times height divided by two now hopefully we know that we plug in next so base right here the base of the triangle is nine times the height how tall is that triangle three feet and we divide that by 2 so we get 9 times 3 is 27 divided by 2 so our area and this one's actually going to give us a decimal 13 and 1/2 or 13 and 5 tenths square feet and lastly number 4 here so we start with the formula area equals base times height divided by 2 now we need to plug in so our base down here is 5 yards and we multiply it by our height now our height is outside the triangle because we need to see how tall it is that's fine due to the shape of the triangle we have that measurement outside but it still is the height so 5 yards times 6 yards and we divide that by 2 so we get area equals 30 divided by 2 and area equals 15 square yards so there you have it that's how you calculate the area of a triangle base times height divided by 2 hopefully that helped out thanks so much for watching until next time peace