Understanding Triangles for Grade 9

Front

Equilateral triangle

Back

Front

Isosceles triangle

Back

sides equal, two equal angles

Front

Scalene triangle

Back

sides and angles different

Front

Right triangle

Back

Front

Acute triangle

Back

Front

Obtuse triangle

Back

Front

Triangle angle sum

Back

Front

Area formula (base and height)

Back

latex="A = \frac{1}{2} \times \text{base} \times \text{height}">

Front

Area formula (Heron's formula)

Back

Front

Area formula (two sides and included angle)

Back

latex="A = \frac{1}{2} ab \sin C">