Education Technology

# Activities

• ##### Subject Area

• Math: Geometry: Triangles

9-12

60 Minutes

• ##### Device
• TI-89 / TI-89 Titanium
• TI-92 Plus / Voyage™ 200

## Heron's Formula

#### Activity Overview

Students use Heron's formula as a functional module and calculate the area of triangles given their sides.

#### Before the Activity

• See the attached PDF file for detailed instructions for this activity
• Print pages 1 - 6 from the attached PDF file for the class
• #### During the Activity

Distribute the pages to the class.

• Study Heron's formula for the area of a triangle and store it as a function
• Calculate the area of a right triangle with given sides
• Calculate the area of other triangles and interpret the possible error messages
• Investigate the proof of Heron's formula
• Determine the area of a trapezoid with given sides and define a general function
• Draw the function and determine an approximate domain and range
• Solve the category C1 exam questions provided on the activity sheet
• #### After the Activity

Students complete the exercises listed on the activity pages.

Review student results.

• As a class, discuss questions that appeared to be more challenging
• Re-teach concepts as necessary