Triangle worksheets contain recognizing and identifying triangles based on sides and angles; finding interior and exterior angles; simple algebra problems; area and perimeter of triangle; finding area for special triangles such as equilateral, isosceles and scalene; advanced topics such as triangle inequality theorem, largest and smallest angle, shortest and longest side and finding centroid.
For basic triangle recognition practice and charts, please refer 2D Shapes Worksheets
Identifying Triangles Based on Sides
Label each triangle. Based on sides, you can classify triangle as equilateral, isosceles and scalene. Use ruler wherever necessary.
Identifying Triangles Based on Angles
Label each triangle. Based on angles, you can classify triangle as acute, obtuse and right.
Identifying Triangles: Both Sides and Angles
Classify each triangle by considering the measures of both sides and angles.
Classifying Triangles: Select all that apply
There are types of triangles along the row and different triangle images along the column. Tick the boxes that apply to each triangle.
Angles in Triangle
Finding Interior Angle
Apply angle sum theorem to find the unknown interior angle in each triangle.
Finding Exterior Angle
Applying exterior angle theorem, find the measure of an exterior angle in each triangle.
Algebra in Triangles
Identifying Unknown Interior Angle
Find the value of x. Using x value, find the measure of unknown interior angle.
Identifying Unknown Exterior Angle
Set the equation applying exterior angle theorem and find the value of x. Also find the missing exterior angle.
Finding length of the Sides
With the perimeter and algebraic expressions, set the equation and find the value of x. By applying the value of x, compute the length of all the sides of a triangle.
Perimeter of Triangle: Standard
Add up the lengths of all the sides and find the perimeter of a triangle.
Perimeter of Triangle: Congruent Properties
Find the perimeter with the given measures and congruent sides.
Area of Triangle: Base and Height
Using the formula A = 1/2 * base * height, find the area of each triangle. Challenging worksheet requires unit conversion.
Area of an Equilateral Triangle
Use the formula A = sqrt(3)/4 * a2, where 'a' refers to length of the side. Each worksheet has 9 problems finding area of an equilateral triangle.
Area of an Isosceles Triangle
Find the height using Pythagorean theorem, and then apply the standard formula to find the area of each isosceles triangle.
Area of Scalene Triangle
Apply Heron's formula (also called Hero's formula) to find the area of each scalene triangle. Round the answer to 2 decimal places.
Missing base or height
To find the base, B = 2A / H. To find the height, H = 2A / B. Applying this technique, find the missing side for each triangle.
Advanced Triangle Worksheets
Relation between Sides and Angles
Each worksheet has 2 sections. In first section, find the largest and smallest angle with known sides. In second section, find the longest and smallest side for each triangle with known angles.
Triangle Inequality Theorem
Apply triangle inequality theorem and identify whether the triangle is possible or not possible with the given sides.
Each worksheet has 9 problems finding centroid of each triangle with coordinates at vertices.