Question

ABC is a straight line.

The length AB is five times the length BC .

AC =90 cm.


Work out the length AB .


(3 marks)

Answer 1

• 75 cm

Explanation:

According to segment addition postulate we have:

• AC = AB + BC

We are given:

• AB = 5 BC

Then substitute values into the first equation:

• AC = 5 BC + BC
• 90 = 6 BC
• BC = 90/6 = 15 cm

Find the length of AB:

• AB = 5*15 cm = 75 cm