Circles, Arcs & SectorsCambridge IGCSE Maths: Flashcards

Card 1 of 150 of 15 known

Question

What is the formula for the circumference of a circle?

Tap or press Space to reveal

Tap card or press Space to flip

See all 15 cards

What is the formula for the circumference of a circle?: C = 2πr (or C = πd)
What is the formula for the area of a circle?: A = πr²
What is an arc?: A portion of the circumference of a circle.
What is a sector?: The 'pie-slice' region of a circle bounded by two radii and an arc.
What is the formula for arc length given angle θ at the centre?: arc length = (θ/360) × 2πr
What is the formula for sector area given angle θ at the centre?: sector area = (θ/360) × πr²
What is the minor arc?: The shorter of the two arcs created by two points on a circle.
What is the major arc?: The longer of the two arcs created by two points on a circle.
At Core level, what restriction applies to the sector angle?: It must always be a factor of 360°.
What does 'give your answer in terms of π' mean?: Leave π as a symbol in the final answer instead of converting it to a decimal.
A circle has radius 5 cm. What is its circumference in terms of π?: C = 2π(5) = 10π cm
A circle has radius 4 cm. What is its area in terms of π?: A = π(4)² = 16π cm²
What common mistake happens when a diameter is given instead of a radius?: Using the diameter directly in A = πr² without halving it first, giving an area four times too large.
A sector has radius 9 cm and angle 40°. What fraction of the full circle is this?: 40/360 = 1/9 of the full circle.
What value of π should be used without a calculator?: 3.142