Content domain
Geometry & Trigonometry.
Geometry & Trigonometry makes up approximately 15% of the Digital SAT Math section. Questions test area and volume, angle relationships, triangle properties, right-triangle trigonometry (SOH-CAH-TOA), and circles. The reference sheet provided during the test includes key formulas, but knowing them cold saves time.
Subtopics
Area and volume
Area of triangles, rectangles, circles, trapezoids. Volume of boxes, cylinders, cones, and spheres.
Lines, angles, and triangles
Parallel lines cut by a transversal, angle sum in triangles, similar and congruent triangles, the Triangle Inequality.
Right triangle trigonometry
SOH-CAH-TOA, 30-60-90 and 45-45-90 special triangles, the Pythagorean theorem.
Circles
Circumference, area, arc length, sector area, central angles, and inscribed angles.
Coordinate geometry
Distance and midpoint formulas, the equation of a circle (x−h)²+(y−k)²=r², parabolas in the coordinate plane.
Key formulas
a² + b² = c² (Pythagorean theorem) A = ½bh (area of a triangle) A = πr² (area of a circle) C = 2πr (circumference) L = (θ/360) × 2πr (arc length) V = πr²h (volume of a cylinder) sin θ = opp/hyp, cos θ = adj/hyp, tan θ = opp/adj 30-60-90: x, x√3, 2x | 45-45-90: x, x, x√2 Test-taking tips
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Draw and label diagrams for every geometry problem — even when one is already provided.
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Memorize 30-60-90 and 45-45-90 ratios; they appear in nearly every test.
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Arc length and sector area are proportional to the central angle divided by 360.
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For right-triangle trig, the key is correctly identifying opposite, adjacent, and hypotenuse relative to the reference angle.