hot to find an angle of an obtuse triangle with only 2 sides and the area?

Question

please help, urgent!

Answer 1

-use a^2 + b^2 = c^2 to find the other side of the triangle

-then use sin, cos, or tan to find the angles...

Answer 2

Interesting problem.

If it is the obtuse angle that you are trying to find; I would start by sketching the triangle with one of the known sides as the base. Since you know the area, you can calculate the altitude. Using that and the other given side, calculate the exterior angle using the sine function. The obtuse angle will be the supplement of the external angle.

Answer 3

You have 2 sides known and the area know
So, you can write:

If the sides of a triangle are a, b, and c
The angles are A, B, C

You have:
Area = 1/2 *ab*sinC = 1/2 * bc*sinA = 1/2 *ac*sinB

Furthermore, since sin A = sin (pi - A) = sin (B + C), and similarly for the other two angles:

Area= 1/2 *ab*sin(A+B) = 1/2 *bc*sin(B+C) = 1/2 *ac*sin(A+C)

Answer 4

Area = .5 bc sinA = .5 ca sinB = .5 ab sinC, where:
A, B and C are the three angles of the triangle
and a,b and c are the sides opposite these angles.

So angle A = arcsin (Area/(.5bc))
So angle B = arcsin (Area/(.5ac))
So angle C = arcsin (Area/(.5ab))

Answer 5

Area = Sq,rt. of s(s-a)(s-b)(s-c) where s = (a+b+c)/2
Find the third side. Use sin, cos, tan to find the angle