Posted by Nicole on .
How do you go about finding the lateral area of a trianglar prism?
Ex: The base of a triangular prism is an equilateral triangle with a perimeter of 42 cm. If the height of the prism is 10 cm, find the lateral area.
Thanks for the help in advance

Geometry 
drwls,
Each of the three rectangular sides of the prism has an area of 14 x 10 = 140 cm^2. So there are 420 sq. cm of lateral area consisting of rectangles.
There are also two triangle sides. An equilateral triangle with 42 cm perimeter has 14 cm sides and a height of 14 sin 60 = 12.12 cm
The area of each triangular end is therefore
(1/2)x14x12.12 = 84.9 cm^2
Add 2 x 84.9 to 420 cm^2 for the answer.