IB Math AA SL · Topic 3
Geometry and trigonometry
Two courses in one topic. The first three sections are measurement — distances, solids, triangles — and are shared with the other SL course, in degrees. From SL 3.4 the topic turns to radians, the unit circle and identities, which is where the topic becomes algebraic and where exact, no-calculator working matters most.
What the syllabus covers
Eight assessed sections, SL 3.1 to 3.8 — measurement first, then the circular functions.
How it is examined
The topic splits cleanly across the two papers: exact values and identities with no calculator, triangles and sectors with one.
From SL 3.4 onwards the guide's convention is that radian measure is assumed on examination papers unless degrees are indicated. SL 3.1 to 3.3 are shared with the other SL course and are normally in degrees — read the unit before you read the numbers.
Paper 1 (no calculator) tests the unit circle and the identities in exact form: the exact value of sin(π/3), or cos 2θ given sin θ = 3/5, without ever finding θ. Decimals from a calculator are not what is being asked for.
Paper 2 (technology) sets triangle and sector problems with measurements: the sine and cosine rules, the area formula, the ambiguous case, arc length and sector area. The GDC must be in the right angle mode.
Equations are solved on a stated interval, and every solution in that interval is a separate mark. Finding one solution of sin x = ½ and stopping is a common way to lose an accuracy mark.
Equations that reduce to a quadratic — 2sin²x − sin x − 1 = 0 — are solved as a quadratic first, in sin x, and then as trigonometric equations; rejecting a value that is outside the range of sine is part of the answer.
In SL 3.1 the volume and surface-area formulae are given in the formula booklet, but not which length plays which role: separating height from slant height is where the work is.
A marked question, mark by mark
A trigonometric equation on an interval: the method is right, and the second solution is the mark that disappears.
Rehearse both papers' styles, on fresh exercises
From SL 3.1 solids to SL 3.8 equations, every generated exercise is written in the style of Paper 1 or Paper 2 as the question demands — with radians stated where they apply — and comes back mark by mark.
Start your trialNew to the codes? M1, A1, R1 explained →
Trigonometric equations · SL 3.8
Seed 5N60
Solve the equation 2 sin x = 1 for 0 ≤ x ≤ 2π.
- (a)Find all solutions in the given interval, giving exact answers.
Your work
sin x = 1/2
x = π/6
Marks awarded
- M1Mark awarded. Rearranged to sin x = 1/2 and recognised the exact value.
- A1Mark awarded. x = π/6, an exact solution in the interval.
- A1Mark not awarded. The second solution in the interval, x = 5π/6 (π − π/6), is missing.
Where marks are actually lost
Trigonometry rewards accuracy of setting more than accuracy of calculation.
Leaving the GDC in the wrong angle mode — degrees for a radian question, or the reverse.
CostEvery value is wrong at once. The method marks may survive; each accuracy mark that depended on a calculator value does not.
Stopping at the first solution of a trigonometric equation.
CostEach solution in the interval carries its own mark, so a missing solution costs an accuracy mark even when the first one is exact.
Ignoring the ambiguous case when the sine rule is used with two sides and a non-included angle.
CostThe second triangle, with the obtuse angle, is part of what the question tests; giving only the acute angle earns only part of the accuracy marks.
Replacing exact values with calculator decimals when the question asks for an exact answer.
Cost√3/2 and 0.866… are not interchangeable on an exact-value question; the method mark remains, the answer mark does not.
Other Math AA SL topics
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