NABTEB Mathematics 2024 Objective — Question 23

Question 23 of 50 from the National Business and Technical Examinations Board (NABTEB) Mathematics 2024 Objective paper, with the correct answer and a full explanation.

In the diagram, O is the centre of the circle. If |OA|=25cm and |AB|=40cm, find |OH|.

• A. A. 15cmCorrect
• B. B. 20cm
• C. C. 25cm
• D. D. 30cm

Explanation

OH is perpendicular from centre O to chord AB, so it bisects AB: AH=HB=20cm. In right triangle OHA: OA²=OH²+AH². 25²=OH²+20². 625=OH²+400. OH²=225. OH=15cm.

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