SPM 2024 Add Maths Paper 1, Question 4Circular Measure

Solved on video in English and Bahasa Melayu · Form 5, Circular Measure · 2:39 video

The question

Diagram 5 shows a circle with centre O and an arc AB which subtends an angle θ rad at O. It is given that the radius of the circle is r unit and the length of the minor arc AB is s unit. Based on Diagram 5, derive s = rθ.

Step 1

Use the proportion concept: the ratio of arc length to full circumference equals the ratio of the subtended angle to the full angle.

Why this step

'Derive' means show where s = rθ comes from. The arc is the same fraction of the circumference as θ is of the full angle 2π.

3 more steps, each with the reason for it, in the full solution

Final answer

Shown: s = rθ

Where students lose marks

Watch out: don't just quote s = rθ from memory. Start from the proportion s / (2πr) = θ / (2π) and show your working.

Watch every step of this question solved on video (2:39), with the reason behind each step and a box that checks your own answer.

Start 7 days freeAlready a member? Watch it now

No card. Every past-year question on video, in English and BM.

All questions in SPM 2024 Paper 1

Circular Measure: lessons and every past-year question

Baca dalam Bahasa Melayu

More Circular Measure questions

Questions are re-typeset by Eduly for study and commentary. Eduly is not affiliated with Lembaga Peperiksaan Malaysia or the Ministry of Education.