Flashlights use total internal reflection by using a light bulb as a source of light. The light bounces off of the lenses located underneath the light bulb. When The incoming rays travel parallel to one another and reflects off a smooth surface, the Reflected ray is the same as the incident ray.

As such, modern LED flashlights have LEDs mounted and oriented in a roughly parallel manner, with directional optics. The resulting light output is generally round in shape unless precise optics are added to shape the light output into narrower or special applications, illuminating traffic control devices.

octahedron

Lesson Summary An example of a ray is a sun ray in space; the sun is the endpoint, and the ray of light continues on indefinitely. In another example, a person hitting a tennis ball could cause it to travel in a ray if there were no resistance from the air; however, this can’t happen on earth due to friction.

RAY

• flashlights.
• arrow.
• projector.

A ray is a part of a line that has one endpoint and goes on infinitely in only one direction. You cannot measure the length of a ray. A ray is named using its endpoint first, and then any other point on the ray (for example, →BA ).

Obtuse angles are seen on most house rooftops, as the two roof surfaces slope down from it. Other real world examples of an obtuse angle include the angle between the screen and the base of an opened laptop, a hockey stick, an accordion hand fan and between the wings of a boomerang.

Straight Angle Examples A flat surface has an angle of 180 degrees. A straight stick has an angle which is straight or 180 degree. A plane inclined staircase represents a straight angle. Angle formed in a see-saw.

A right angle is an angle that measures 90°. It is the most commonly seen angle in our day-to-day life. It can be seen in the corners of a room, the edges of boxes, the screen of a mobile phone, and so on. The sides of a square and a rectangle always form a right angle with each other.

When it is three o’clock, the two hands of the clock are on digits 12 and 3. The seconds hand moves between these two digits and forms a pair of complementary angles in real life. The sum of the two angles formed by the seconds hand is always 90 degrees.

Three angles or more angles whose sum is equal to 90 degrees cannot also be called complementary angles. Complementary angles always have positive measures. It is composed of two acute angles measuring less than 90 degrees.

Two angles are called complementary when their measures add to 90 degrees. Two angles are called supplementary when their measures add up to 180 degrees.

If you add up the two angle measures, the sum is equal to 90 degrees. Therefore, the two angles are complementary.

180 degrees

vertical angles

When the lines are parallel, the corresponding angles are congruent . When two lines are cut by a transversal, the pairs of angles on one side of the transversal and inside the two lines are called the consecutive interior angles .