## Elementary Geometry for College Students (6th Edition)

Area = =$\frac{1}{2}$*5*7*sin56°
Given, a=5, b=7, α = 36° , β =88° As we know the sum of all the angles of the triangle is 180° in triangle ABC, α + β + γ = 180° 36° + 88° + γ = 180° γ = 180° - 36° - 88° γ =56° By theorem 11.4.1 Area of triangle = $\frac{1}{2}$a*b*sinγ =$\frac{1}{2}$*5*7*sin56°