Final: Master of Triangles

Part of the Triangles section of Coddy's Geometry journey. Lesson 60 of 60.

A roof truss is an isosceles triangle. Its two sloping beams are 13 m each, and the horizontal beam along the bottom is 24 m. An upright post runs from the peak down to the middle of the bottom beam, meeting it at a right angle.

Find the area of the triangle and the total length of its three outer beams.

Challenge

The truss △ABC has AB = AC = 13 and BC = 24, with the post AD to the midpoint D. Find both its area and its perimeter, then press Check.

Try it yourself

$Find the marked part of the figure$

Find the marked part of the figure

All lessons in Triangles

1The Triangle Inequality

Can Three Sticks Meet?Exactly Reaching The Range of the Third Side Recap: The Third Side

4Area of a Triangle

Half the Rectangle Height Is Not a Side Right Triangle Area Finding the Height Any Side Can Be the Base Recap: Area

7Is It Right?

The Converse Testing a Triangle Acute or Obtuse?Sorting by the Test Recap: Right or Not

10Scale in the World

Shadows Across the River Nested Triangles A Side with an Expression Recap: Scale in the World

2Sides and Names

Sorting by Sides The Longest Side Ticks into Equations Recap: Sorting Triangles

5The Pythagorean Theorem

Squares on the Sides Finding the Hypotenuse Pythagorean Triples When It Is Not Whole Recap: The Hypotenuse

8Special Right Triangles

The 45-45-90 Triangle Legs from the Hypotenuse The 30-60-90 Triangle All Three Sides Which Triangle Is It?Recap: Special Triangles

11Two Tools at Once

Height of an Isosceles Area from the Height The Equilateral Triangle Right Triangle Perimeter Recap: Two Tools

3Perimeter

Around the Edge A Missing Side Isosceles Perimeter Sides as Expressions Recap: Around the Edge

6Finding a Leg

Working Backwards The Ladder Which Side Is c?A Leg That Is Not Whole Recap: Finding a Leg

9Similar Triangles

Same Shape, Different Size The Scale Factor Finding a Side Matching the Corners Recap: Similar Triangles

12Final Challenges

Final: Three Sticks Final: The Fence Final: The Ladder Final: The ShadowFinal: Master of Triangles