I barely remember anything from this week so I am just going to go over section 9-3, Law of Sines.


This is only with non-right triangles, and you only use it when you have an angle and opposite leg value you know.

Formula:sin(angle)/opposite leg=sin(angle 2)/opposite leg 2*Cross multiply to solve.Ex. In triangle ABC, AB= 25; A=110; and B=20. Find AC and BC.
Draw the triangle. You will find the missing angle by 180-110-20=50.
So, sin50/25=sin110/BC.
Cross multiply to get:
BC=25sin110/sin50BC=30.667 m
Now to find AC: sin50/25=sin20/AC
AC=25sin20/sin50
AC=11.162 m

Ex. 2
In triangle RST, angle S=126 degrees, s=12, t=7. Determine whether angle T exists. If so, find all possible measures of angle T.
sin126/12=sinT/7T=sin^-1(7sin126/12)T=28.159 degrees

Now you must find another angle. Sin is related to Y and is positive in Q I and II.-28.159+180=151.841

Now you test the angles in the triangle. 151.841 + 126 exceeds 180. So the only angle that can work, is 28.159.


kthanksbye.