angles, circles, arcs & sectors
Quick links:
► downloadable teaching materials for angles, circles, arcs & sectors
► syllabus content for the Trigonometry Topic: SL syllabus (see syllabus section 3.1); HL syllabus (see syllabus section 3.1)
Most questions involving circles, radian measure, arcs and sectors require what I like to refer to as geometric problem solving. This kind of problem solving puts a lot of emphasis on carefully interpreting (and possibly constructing) geometric diagrams, coming up with some visual and/or geometric insights involving a diagram, and then organizing a solution strategy that will lead to a correct answer.
Although there are formulas that need to be applied to solve this question, the most important consideration is devising a successful solution strategy from analyzing the diagram ... geometric problem solving. Many students are not confident in analyzing geometric diagrams, so it is important to give your students ample practice in solving problems that require a certain amount of geometric insight leading to the application of appropriate principles and formulas to obtain the correct solution.
4 questions - ‘accessible’ to ‘discriminating’
download: 
4_Qs_circles_arcs_sectors_1_with_answers 
accessible SL question
moderate SL / accessible HL question
discriminating SL / moderate HL question
discriminating HL question
Answers
Course planning / teaching notes:
♦ teaching materials
EXS_3-1-20v2_SLHL_trig_radian_arc_sector
Exercise set with 10 questions covering radian measure, arc length & sectors (corrected version 2)
EXS_3-1-20_Q10_solution
worked solution for question # 10 in trig, radian, arc, sector exercise set above