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GeoGebraGeoGebra Lesson

Finding the Area of a Triangle Using Trigonometry

Explore how the area of a triangle relates to two side lengths and the sine of their included angle.

Task 1

Putting It All Together

Answer these open ended questions on your own or with others to form deeper math connections.

Task 2

Two sides of a triangular paddock measure 20 and 15 yards, and the angle between them is 45°. Find the area of the paddock.

Task 3

Two sides of a triangular paddock measure 20 and 15 yards, and the sine of the angle between them is 4/5. Without calculating the area, can you determine which paddock has the greater area: this one or the one in the previous problem? Verify your conjecture by calculating the area of this paddock.