Education Technology

# Activities

• ##### Subject Area

• Math: Algebra II: Trigonometric Functions

9-12

40 Minutes

• ##### Device
• TI-Nspire™ CX/CX II
• TI-Nspire™ CX CAS/CX II CAS
• TI-Nspire™
• TI-Nspire™ CAS
• ##### Software

TI-Nspire™
TI-Nspire™ CAS

3.2

• ##### Other Materials
By Lynne Plettenberg

## Ain't No River Wide Enough

#### Activity Overview

Students simulate the process a surveyor would use to measure the width of a river by measuring length on one side of the river and angles formed by various reference points. They then prove the Law of Sines and apply it to calculate the river's width, proving that no river is too wide to be measured with trigonometry.

#### Key Steps

• In this problem, students investigate a scenario of a team building a bridge. Students work as a team to find some ideas on ways to measure the width.

• Students drag the point until they come to the proposed path, where the road intersects the riverbank. They use the intersection command to put a point as a stake between the road and riverbank and label it S2.

• Students draw a triangle using their current points. They should see that the triangle is a right triangle and they can use the Law of Sines to find the missing sides.