Recall the following formula:
Given a triangle with side lengths a, b, and c. Let the measure of the angle between sides of length a and c be B.
Then, the area of the triangle is given by :
.
In our example we have: Area=10 square cm, a=8 cm, c=5 cm, and we want to find the measure of the angle between the 2 sides a and c.
Substituting in the formula we have:
Thus,
, which means 
.
is the sine of 
, but also 
.
Answer: both 30, and 150 degrees are possible
Given a triangle with side lengths a, b, and c. Let the measure of the angle between sides of length a and c be B.
Then, the area of the triangle is given by :
In our example we have: Area=10 square cm, a=8 cm, c=5 cm, and we want to find the measure of the angle between the 2 sides a and c.
Substituting in the formula we have:
Thus,
Answer: both 30, and 150 degrees are possible