☰ Year plan · Mathematics

The isosceles triangle

Week 11 · The isosceles triangle: base angles, the equilateral triangle, axis of symmetry and the 30°–60°–90° triangle · 3 lessons
Answers are for parents and teachers.
1
In an isosceles triangle the vertex angle is 100°. Find each base angle.
2
In an isosceles triangle with AB = AC, B = 4x − 10 and C = 2x + 20. Find x and the vertex angle.
3
Isosceles Δ ABC has AB = AC = 25 cm and BC = 14 cm. Find the height from A and the area.
4
In a 30°–60°–90° triangle the long leg is the short leg times √3. If the short leg is 9 cm, find the hypotenuse and the long leg.
5
A ramp makes an angle of 30° with the ground and is 6 m long. What height does it reach?