What is the area of this triangle?

 

 

 

 

 

 

 

 

 

 

 

Method 1

Draw perpendicular BD.

Use basic trigonometry to find length of BD.

(This is the height of the triangle.)

 

Then use

A = ½ x base x height

 

 

So

 

 

 

 

A = ½ x base x  height

A = ½  x 12 x 9.511

A = 57.063391

A = 57.1 cm²   (1 dp)

 

 

 

Method 2

Name sides opposite vertices with their lower case letters.

 

 

 

 

 

 

 

 

 

 

 

A = ½  x base x height

A = ½  x b x csinA

A = ½  bcsinA