NINE FOURRRRRRR

This week in Advanced Math, our seventh hour honors advanced math class finished learning about and later tested on chapter nine. In section four chapter nine, my class learned about the Law of Cosines. This law is used for non-right triangles which is a triangle without a 90 degree angle. [For a 90 degree angle use SOHCAHTOA.]
The formula is: (opposite leg)^2 = (adjacent leg)^2 + (adjacent leg)^2- 2 (adjacent leg) (adjacent leg) cos (angle between)

So, for this section only one example is necessary. And the example is………

Suppose two sides of a triangle have lengths 4cm and 8cm and the angle between them measures 140 degrees. Find the third side.

A). Draw your triangle and label it.

B). We know that 4cm and 8cm are our adjacent legs and 140 degrees is our angle . So plug these numbers into the formula – x^2=8^2 +4^2 -2(8)(4)cos140 degrees

C). Since everything is squared, you must find the square root. Square root everything and plug
it into your calculator.

D). Your answer is 11.4