Example 1 Easy
A triangle has angle measures 50 degrees, 60 degrees, and x degrees. What is x?
- 60
- 70
- 80
- 90
Show answer and explanation
Answer: 70
Triangle angles add to 180 degrees. So x = 180 - 50 - 60 = 70.
SAT Math skill page
SAT Geometry Practice
Review the SAT geometry moves that turn diagrams into equations and formulas into points.
12-18 min practice time 3 examples on page Geometry and Trigonometry
What this tests
What to know for this SAT skill
- Use triangle angle sums and line angle relationships
- Find perimeter and area from dimensions
- Apply circle circumference and area formulas
- Translate diagram labels into equations
Practice examples
Try a few SAT-style questions
Example 2 Medium
A rectangle has length 10 and perimeter 34. What is its width?
- 5
- 7
- 12
- 14
Show answer and explanation
Answer: 7
Perimeter is 2(length + width). So 34 = 2(10 + w), which gives 17 = 10 + w and w = 7.
Example 3 Hard
A circle has circumference 18pi. What is its area?
- 18pi
- 36pi
- 81pi
- 324pi
Show answer and explanation
Answer: 81pi
Circumference is 2pi r. If 2pi r = 18pi, then r = 9. The area is pi r^2 = 81pi.
Avoid these traps
Common mistakes on this skill
Using the wrong formula
Circle circumference and area both use pi, but circumference is 2pi r and area is pi r squared.
Forgetting angle totals
Triangles add to 180 degrees, straight lines add to 180 degrees, and full circles add to 360 degrees.
Mixing up radius and diameter
The diameter is twice the radius. Check which one the question gives before using a circle formula.
Study plan
How to practice this skill in Dolphin
- Memorize the high-frequency SAT geometry formulas.
- Label diagrams with every given and inferred value.
- Write a short equation before trying answer choices.
- Check units: length, square units, and cubic units are not interchangeable.
Related practice
Build the surrounding skills
FAQ
Questions about SAT Geometry Practice
How much geometry is on SAT Math?
Geometry is a smaller but important part of SAT Math. It often appears through triangles, circles, angles, and area.
Are formulas provided on the SAT?
Some formulas are provided, but you still need to know when and how to use them quickly.
What is the best way to study SAT geometry?
Practice recognizing the formula or relationship a diagram is asking for before doing calculations.