Rays and Angles Honors Math – Grade 4

Review  Name this line 6 ways. M O N NName this line 12 ways. RXYS

Ray  A ray is a straight figure with one endpoint.  A ray goes on forever in one direction.  Read: ray KJ  Write:  Always read the endpoint of a ray 1 st. K J BA

Angle AAn angle is formed by two rays with the same endpoint. TThe rays form the sides of the angle. TThe endpoint is the vertex of the angle. RRead: angle Q, angle PQR, or angle RQP. WWrite: WWhen you use 3 letters to name an angle, the vertex is always the middle letter. R P Q A C B

Right Angle WWhen two sides of an angle form a square corner, the angle is called a right angle. AAngle Y is a right angle. ZY X

Acute Angle  An acute angle measures less than 90 degrees.  We use a protractor to measure an angle by measuring the distance between its sides.

Obtuse Angle AAn obtuse angle is greater than 90 degrees. UUse a protractor to measure angles.