Illustrative Mathematics
Finding an Unknown Angle
Teach your class how to apply their knowledge of geometry as they explore the unknown. In order to find an unknown angle, students must understand that rectangles have four interior right angles, that right angles have 90 degrees, and...
EngageNY
Unknown Angles
How do you solve an equation like trigonometry? Learners apply their understanding of trigonometric ratios to find unknown angles in right triangles. They learn the meaning of arcsine, arccosine, and arctangent. Problems include basic...
EngageNY
Unknown Angle Problems with Inscribed Angles in Circles
We know theorems about circles—now what? Class members prove a theorem, with half the class taking the case where a point is inside the circle and half the class taking the case where a point is outside the circle. The lesson then...
EngageNY
Solve for Unknown Angles—Angles and Lines at a Point
How do you solve for an unknown angle? In this sixth installment of a 36-part series, young mathematicians use concepts learned in middle school geometry to set up and solve linear equations to find angle measures.
EngageNY
Unknown Angle Proofs—Proofs of Known Facts
Lead the class in a Greek history lesson with a geometric twist. Pupils relate a short video about geometric properties to modern-day methods of solving for unknown angles. They discuss parallel line theorems and complete practice...
Curated OER
Geometry - Angles Overview
Learners address 14 questions that include naming all pairs of opposite and supplementary angles for sets of intersecting lines and then, finding the measure of the unknown angle. They determine the measure of the angle that is...
EngageNY
Solve for Unknown Angles—Angles in a Triangle
Assist your class with each angle of geometry as they use exterior angles to form linear pairs with adjacent interior angles. They cover multiple vocabulary terms and work practice problems, complete with justifications, before taking an...
CK-12 Foundation
Angle Measurement: Adding Angles
Build angles from angles. Using the Angle Addition Postulate, learners find the measures of unknown angles. The interactive simulation shows a visual representation of the postulate and allows individuals to manipulate the angles and...
Curated OER
Measurements of Unknown Angles
In this geometry skills practice worksheet, students respond to 9 questions that require them to calculate the measurements of the unknown angles.
Curated OER
Kuta Software - Angles in Quadrilaterals
In this angles in quadrilaterals worksheet, students solve 18 short answer problems. Students find unknown angles in a quadrilateral given a sketch of various quadrilaterals with unknown angle measurements.
Curated OER
Find the unknown angle in the following triangles
In this unknown angle worksheet, students find the unknown angle in the triangle that gives them 2 angles. Students find 9 unknown angles.
Curated OER
Five Find the Unknown Angle Interactive Problems
In this unknown angle worksheet, students use trigonometry functions in five problems to find the unknown angles. Students may check their solutions and receive hints by using the "Check" and "Hint" button found at the bottom of the page.
EngageNY
Sine and Cosine of Complementary Angles and Special Angles
Building trigonometric basics here will last a mathematical lifetime. Learners expand on the previous lesson in a 36-part series by examining relationships between the sine and cosine of complementary angles. They also review the ratios...
University of Utah
Geometry: Angles, Triangles, and Distance
The Pythagorean Theorem is a staple of middle school geometry. Scholars first investigate angle relationships, both in triangles and in parallel lines with a transversal, before proving and applying the Pythagorean Theorem.
Curated OER
Geometric Properties
Students find triangular angles using the angle theorem. In this geometry instructional activity, students describe labeled triangles, use the pythagorean theorem, and rewrite information about triangles in standard form.
Curated OER
Finding Unknown Angles
In this finding unknown angles worksheet, 10th graders find each numbered angle's measure for 20 different angles shown in the diagrams. They calculate the size of an angle when the other two angles are known to equal 180 degrees. Then,...
Flipped Math
Inverse Trig Ratios
Put trigonometric ratios into inverse. Scholars learn how to find an unknown angle in a right triangle by using inverse trigonometric ratios. The pupils understand how the inverses undo a trigonometric ratio to provide the angle measure....
Illustrative Mathematics
Find the Missing Angle
This one activity requires young geometers to pull together information they are currently learning with things they have learned previously. Here they rely on understanding something about parallel lines, alternative interior angles,...
McGraw Hill
Triangles
After reviewing characteristics of seven types of triangles, young geometers discover how to find the missing angle of a triangle. Then, they practice identifying triangles, find missing angles, and find missing side lengths of similar...
Curated OER
Tests for Parallelograms Homework
In this test for parallelograms activity, students solve 15 short answer problems. Students determine if a given sketch is a parallelogram given angle measures and/or side lengths. Students use knowledge of parallelograms to find unknown...
Curated OER
Geometry: Lesson 8
Eighth graders engage in a lesson that is concerned with the finding of angles that are found in different two dimensional figures. They compare and contrast exterior and interior angles while also determining the unknown measures of...
Curated OER
Academic Grade 9 Assessment of Mathematics: Algebra I and Geometry
Test your class, or use this 12 page math packet as chapter review. They solve 21 multiple choice problems which require them to graph linear equations, find the volume of prisms and cones, find unknown angles, and determine...
EngageNY
One-Step Problems in the Real World
Mirror, mirror on the wall, which is the fairest resource of them all? Individuals write and solve one-step equations for problems about angle measurement, including those involving mirrors. Both mathematical and real-world problems are...
Curated OER
Introduce Vocabulary: Pinkalicious (Kann)
Although the title of Elizabeth Kann's story Pinkalicious isn't a real word, the book is an excellent way to explore some new vocabulary in context: acute, mushy, rare, steady, and surrounded. Find the story free on YouTube if you don't...