MathCastle
Grade 6HardArea of Triangles

Area of Triangles · Hard problem

A triangle has corners at (0,0)(0, 0), (9,3)(9, 3) and (3,9)(3, 9) on a coordinate grid. Paint for the triangular region costs $0.50\$0.50 per square unit. How much does it cost to paint the whole triangle, in dollars?