Area of a Triangle What is a triangle

Area of a Triangle

What is a triangle? All triangles are related to rectangles or parallelograms: You can draw a diagonal line in any rectangle or parallelogram. Each rectangle or parallelogram is made up of two triangles!

What is the Area of a Triangle? The area formula for a rectangle or a parallelogram is: A = bh. Each triangle is ½ of a rectangle or a parallelogram. There are two triangles in these shapes!

The Formula! Remember the area formula for a rectangle or parallelogram is A=bh and that each rectangle and parallelogram has TWO triangles in their shape. Using this information to develop your own formula.

Can I have a drum roll please? ! Without further ado your formula should look something like… The area formula for a triangle is It can also be written as

Finding the Area of a Triangle Determine which measurement is the height: The height is inside the triangle The height is outside the triangle The height is a side of the triangle

Finding the Area of a Triangle Pay close attention to the pictures below. You may notice that some of the triangles have been rotated or hidden in pictures. Find base and height in these examples: base = 10 cm height = 9 cm base = 12. 1 m height = 6. 4 m base = 7 yd height = 4 yd

Applying the Area Formula Write the area formula Rewrite the area formula substituting the values that you know. Solve one step at a time rewriting after each step.

Applying the Area Formula Example: Find the area of the triangle shown below. A = ½ bh A = ½ × 15. 6 × 11. 25 A = ½ × 175. 5 A = 87. 75 square meters

Finding the Area of a Triangle With your shoulder partner find the area of the following triangles using Rally Coach. 1. 2. 3. 4.

Rally Coach 1. Students sit in pairs. 2. First Problem: Partner A solves; Partner B coaches and praises. 3. Next Problem: Partner B solves; Partner A coaches and praises. 4. Continue solving problems.

Finding the Area of a Triangle With your shoulder partner find the area of the following triangles using Rally Coach. 1. Answer: 90 cm 2 2. Answer: 425. 25 mm 2 3. Answer: 45 cm 2 4. Answer: 14 yd 2

Check your Understanding Find the area of the following two triangles independently. 5 cm. 6 ft. 7 cm. 3 ft. 4 mm. 9 mm. 8 km. 11 km.

Check your Understanding Find the area of the following two triangles independently. 1) 9 ft 2 3) 18 mm 2 1) 17. 5 cm 2 3) 44 km 2

Check your Understanding Number Correct 4 I completely understand this skill, can do all problems on my own, and can help others learn. 3 I can do simpler problems on my own but need help to complete the complex problems. 2 I need help to complete all problems whether simple or complex. 0– 1 I do not understand this concept even with help.

Finding the Area of a Triangle From where and how did we derive the area of a triangle formula?