Question

A high school football pennant is in the shape of an isosceles triangle. The base is 18 inches long. The sides meet at an angle of 40°. To the nearest tenth, what is the length of each side?

Answer 1

The length of each side is 26.3 cm

Explanation:

Opposite sides of an isoceles triangle are equal

The isoceles triangle is divided into 2 right-angled triangles so the length of one side can be calculated using trigonometric ratio

When the isoceles triangle is divided, the angle in the right-angled triangle is 20° (1/2 of 40°) and the base is 9cm (1/2 of 18 cm), the hypotenuse side is calculated using trigonometric ratio

Let the length of the hypotenuse side be y

9/y = sin 20°

y = 9/0.3420 = 26.3

Length of each side is 26.3 cm