Student calculates $\bar{y}$ for a triangle.  Must use similar triangles get element $dA$.

Locate the centroid of a rectangle, triangle, and semi-circle on a coordinate grid.

Find the centroid of a shape made up of a rectangle and two triangles.

Find the centroid of a shape made from a rectangle, triangle, and circle.

Draws a triangle based on 3 side lengths.

Draws a triangle based on 3 side lengths and randomises asking for hypotenuse or not.

Homework Set.  Three problems to brush up on trig skills.  Right triangles and sine and cosine law.

Solve a random oblique triangle for sides and angles.

Use the parallelogram rule to solve a force triangle.

Draws a triangle based on 2 angles and a side length.

Draws a right angled triangle based on a length and an angle.

Draws a triangle based on 3 side lengths.

Draws a right angled triangle based on 2 lengths.

Draws a triangle based on 3 side lengths.  Randomises asking angle or side.

Draws a triangle based on 3 side lengths.  Randomises asking angle or side.

Draws a triangle based on 3 side lengths.  Randomises asking angle or side.

Draws a triangle based on 3 side lengths and randomises asking for hypotenuse or not.

Find the missing angle in a triangle using the fact that the angles add to 180 degrees.

Use Pythagoras' Theorem to find the length of a side on a right-angled triangle.

Draws a triangle based on 3 input points. Calculates length, area, perimeter, heights and internal angles

Here you need to choose which formula you would use to find the red dashed value from the solid green values.  The view is three-dimensional and you can rotate it to get a better view.

Variable defintions in the formulas:
$\theta$ is an angle
Adj. is the length of the side adjacent to the known angle
Opp. is the length of the side opposite the known angle
Hyp. is the length of the hypotenuse


Your goal is to get twenty correct answers quickly. Incorrect answers show a highlight of the correct answer to select to continue.  The timer starts as soon as you choose your first answer and continues until you get 20 correct.  Select save answer after your results show in the applet.

Here you need to choose the side of a right triangle relative to the indicated angle shown in green. Your goal is to get twenty correct answers quickly. Incorrect answers show a highlight of the correct answer to select to continue.  The timer starts as soon as you choose your first answer and continues until you get 20 correct.  Select save answer after your results show in the applet.jSpqP5QT

The student is asked to enter a given matrix, but they're only required to fill in the upper triangle.

A custom marking algorithm fills in any empty cells in the lower triangle of the student's answer with the corresponding cell in the upper triangle.

The student is still warned if they leave any cells empty in the upper triangle.

Finding lengths of sides of triangles

Question requires students to determine if the smallest angle of a triangle is smaller than a given value. Answer is Yes/No but students need to use cosine rule to find the smallest angle and to know that smallest angle is oppositeshortest side (otherwise they will need to find all angles of the triangle). Designed for a test where students upload handwritten working for each question as a check against guessing. Also designed to make it difficult for students to google or use AI to find the answer.

Question requires students to determine if the largest angle of a triangle is smaller than a given value. Answer is Yes/No but students need to use cosine rule to find the largest angle and to know that largest angle is opposite longest side (otherwise they will need to find all angles of the triangle). Designed for a test where students upload handwritten working for each question as a check against guessing. Also designed to make it difficult for students to google or use AI to find the answer.

Students are given lengths of 3 sides of a triangle (all randomised) and asked to find one of the angles in degrees. Requires use of the cosine rule.

Area and perimeter of triangles.

Find the reactions of a rigid body (a triangular plate) at a pin and roller, using the three-force body principle.

Two dimensional particle equilibrium problem.  Advice shows how to use how to use slope triangles to find sines and cosines, rather than finding the angle and using that.