SAT Math: Geometry and Trigonometry – What You Need to Know to Succeed

Geometry and trigonometry make up a significant portion of the SAT Math section. While they may not dominate the test like algebra, understanding these topics can give you a competitive edge. Many students overlook them, but mastering just a few core concepts can lead to big score gains.

In this guide, we’ll break down exactly what you need to know about geometry and trigonometry on the SAT, what kinds of questions to expect, and how to prepare effectively.

How Much Geometry and Trigonometry Is on the SAT?

Geometry and trigonometry questions typically make up around 10 to 15 percent of the SAT Math section. These questions may appear in both the calculator and no-calculator sections.

Though fewer in number compared to algebra questions, they are highly valuable because they often test fundamental formulas and reasoning. If you get these right, you can boost your score without needing advanced calculations.

Key Geometry Topics on the SAT

Here are the geometry concepts you need to focus on:

1. Angles and Lines

Understand how to calculate angles formed by intersecting lines, vertical angles, and angles in triangles. Know that the sum of angles in a triangle is always 180 degrees and that parallel lines cut by a transversal create equal angles.

2. Triangles

  • Properties of equilateral, isosceles, and right triangles
  • Pythagorean theorem
  • Triangle inequality theorem
  • Special right triangles (30-60-90 and 45-45-90)

3. Circles

  • Circumference and area
  • Central angles and arc lengths
  • Sector area
  • Equations of a circle in coordinate geometry
    Understanding the formula (x−h)2+(y−k)2=r2(x – h)^2 + (y – k)^2 = r^2(x−h)2+(y−k)2=r2 is key.

4. Polygons and Quadrilaterals

  • Properties of squares, rectangles, parallelograms, and trapezoids
  • Interior angle sums and individual angle measurements
  • Basic area and perimeter formulas

5. Coordinate Geometry

  • Distance formula
  • Midpoint formula
  • Slope and how to identify perpendicular or parallel lines
  • Graphing shapes and understanding their properties in the coordinate plane

Key Trigonometry Topics on the SAT

Trigonometry questions are limited but important, especially since students often neglect this section. Here’s what you need to know:

1. Basic Trigonometric Ratios

Understand sine, cosine, and tangent:

  • sin⁡=oppositehypotenuse\sin = \frac{opposite}{hypotenuse}sin=hypotenuseopposite​
  • cos⁡=adjacenthypotenuse\cos = \frac{adjacent}{hypotenuse}cos=hypotenuseadjacent​
  • tan⁡=oppositeadjacent\tan = \frac{opposite}{adjacent}tan=adjacentopposite​

These are usually applied in right triangle problems.

2. Special Right Triangles

Memorize side ratios of:

  • 30-60-90 triangle: 1:3:21 : \sqrt{3} : 21:3​:2
  • 45-45-90 triangle: 1:1:21 : 1 : \sqrt{2}1:1:2​

These appear frequently in trigonometry questions.

3. The Unit Circle and Radians

You won’t need deep knowledge of the unit circle, but basic understanding of angles in degrees and simple radian conversion (such as π\piπ radians = 180°) can help with occasional advanced problems.

4. Trig Functions in the Coordinate Plane

Some SAT questions place a right triangle on the coordinate plane and ask for sine, cosine, or tangent values using side lengths.

Geometry and Trigonometry Formulas to Know

You won’t be given all formulas on test day, so memorize the most common ones:

  • Area of triangle: 12×base×height\frac{1}{2} \times base \times height21​×base×height
  • Area of circle: πr2\pi r^2πr2
  • Circumference: 2πr2\pi r2πr
  • Pythagorean theorem: a2+b2=c2a^2 + b^2 = c^2a2+b2=c2
  • Distance formula: (x2−x1)2+(y2−y1)2\sqrt{(x_2 – x_1)^2 + (y_2 – y_1)^2}(x2​−x1​)2+(y2​−y1​)2​
  • Slope formula: y2−y1x2−x1\frac{y_2 – y_1}{x_2 – x_1}x2​−x1​y2​−y1​​
  • Special triangle ratios (30-60-90 and 45-45-90)

Tips for Studying Geometry and Trigonometry

  • Practice visuals: Draw and label shapes whenever possible. Visualizing geometry problems makes them easier to solve.
  • Memorize key properties: Especially side ratios and formulas for special triangles and circles.
  • Use practice tests: Focus on official SAT practice problems to see how questions are framed.
  • Don’t overthink: Most geometry questions don’t require complicated calculations. Use logic and known formulas.
  • Check units and labels: Pay attention to what the question is asking—angle measures, side lengths, or coordinates.

Common Mistakes to Avoid

  • Forgetting to label diagrams: Always mark known values to avoid confusion.
  • Confusing similar triangle rules: Review what makes triangles similar or congruent.
  • Assuming all diagrams are to scale: Unless stated, don’t trust visual proportions.
  • Neglecting trigonometry: A few solid points from trig questions can make a big difference in your overall score.

Geometry and trigonometry might not be the largest parts of the SAT Math section, but mastering these areas can be the key to moving from a good score to a great one. By understanding the structure, focusing on the most common topics, and practicing regularly, you’ll walk into test day more confident and ready to handle anything the SAT throws at you.