# More triangles

There is a simple formula for finding the area of a triangle (any triangle, does not have to be right angled).

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It is simply:

Area = ½ ´ AC ´ BC ´ sin C

Or:

Area = ½ ´ AB ´ AC ´ sin A

Or:

Area = ½ ´ BA ´ CB ´ sin B

To use the formula, you must know two side lengths and
the angle **between** those sides.

Find the area of the following triangle: |

Solution |

Area = ½ ´ AC ´ BC ´ sin C Let’s make AC the side of length 6, BC the side of length 7, and 110° the angle C. Then the area is: ½ ´ 6 ´ 7 ´ sin 110º = 19.73 square units. Always check to see whether the answer makes approximate sense – looking at the triangle, 19.73 seems like a reasonable answer for its area. |

Whenever you have to give an area, make sure that you put
units at the end. They could be cm^{2}, mm^{2}, m^{2},
km^{2} or if no units are given, put ‘square units’.