Understanding Elementary Shapes

Understanding Elementary Shapes

By - Ojasvi Gulhane

Angles

In geometry, an angle can be defined as the figure formed by two rays meeting at a common end point.

An angle is represented by the symbol ∠. Here, the angle below is ∠AOB.

Types of Angle

• Acute angle - (Between 0 degree and 90 degree)

• Right angle - (It is perfectly of 90 degree)

• Obtuse angle - (Between 90 degree and 180 degree)

• Straight angle - (it is perfectly of 180 degree)

• Reflex angle - (It is between the 180 degree to 360 degree)

• Zero angle - (It is perfectly of 0 degree)

• Complete angle - (It is perfectly of 360 degree)

Acute angle

• An angle which is measuring less than 90 degrees is called an acute angle. This angle is smaller than the right angle (which is equal to 90 degrees). For example, ∠30^o, ∠45^o, ∠60^o, ∠75^o, ∠33^o, ∠55^o, ∠85^o, etc. ... ∠ABC measures 30 degrees, which is less than 90 degrees and hence it is an acute angle.

• Example - 10 degree , 25 degree ,38 degree ,80 degree

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Right angle

• In geometry and trigonometry, a right angle is an angle of exactly 90° (degrees), corresponding to a quarter turn. ... The presence of a right angle in a triangle is the defining factor for right triangles, making the right angle basic to trigonometry.

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Obtuse angle

• An obtuse angle is a type of angle that is always larger than 90° but less than 180°. In other words, it lies between 90° and 180°. 

• 100 degree,138 degree,140 degree

Straight angle

• A straight angle changes the direction to point the opposite way. It looks like a straight line. It measures 180° (half a revolution, two right angles

Reflex angle

• An angle that is more than 180° but less than 360°

  
  

  (In other words, more than a straight angle, but less than a full rotation.)

• 260 degree,190 degree,223 degree

Complete angle

• Angles that are 360 degrees (θ = 360°) are full turn.v