To “solve the triangle” means to find all
angle and
side lengths. You must have enough information to define a unique triangle. This will take us back to investigating what information was needed to prove
triangle congruencies in Geometry.
1.
AAS

2.
SSS

3.
SAS

2 angles & nonincluded side 
all three sides 
two sides & included angle 




However, if the
triangle does not include a right angle, these basic trigonometric ratios do not apply. Triangles that do not have a
right angle are called
oblique triangles. Although the basic trig ratios do not apply, they can be modified to cover oblique triangles. In this lesson you will discover how to use the cosine
function with oblique triangles.
Law of Cosines
Heron's Area Formula:
Once all three sides of a
triangle are known, Heron's
area formula can be used to calculate its area.
where
Let's practice solving some triangles!