Question

rnell and Donovan are both trying to calculate the area of an obtuse angle. Examine their calculations below. Who is correct and why? 1 2in zin Sin 1 4in Darnell's Work Donovan'. Work

Answer 1

In this case, the correct answer is Donovan's work. We can see that a triangle with an obtuse angle is that one in which one of its angles is greater than 90 degrees and less than 180 degrees. And this triangle is NOT the one with a 90 angle between the sides 3 inches and 4 inches. This is a right triangle (and Darnell's did the calculations for this triangle).

Donovan's work shows the correct answer:

He first takes into account the base: 12 inches, and then the height is the perpendicular distance from the base to the vertex of the obtuse triangle. In this case, this height is equal to 4 inches (it is outside the triangle). We know that the area of a triangle is b * h /2, and he got 24 square inches correctly.