Side Angle Relationship

Two angles that are side by side and that together make a straight line. These angles always add up to equal 180.

Two angles that are side by side and that together form a right angle. These angles always add up to equal 90.

Note: The right angle must be marked with a box.

Two angles that are across from each other at the same vertex (or point). These angles are always congruent (meaning equal).

Two angles that are side by side, but they have no special numeric relationship.

• Identify what type of angles are being shown.

• Determine what the relationship is (add to 180, add to 90, equal, etc.)

• Set up an equation using the relationship.

• Solve for the unknown.