Types of Angles - Class VII

Measure of a right angle is $90^ \circ$

$Obtuse \ angle$ has measure more than that of $right \ angle \ but \ less \ than \ 180\ degree$

$Acute \ angle$ has measure less than $right \ angle$

Angles between $ {0}^{o} $ and $ {90}^{o} $ are acute angles. Hence, $ {89}^{o} $ is an acute angle.

For acute angles triangle all the three angles must be less than ${ 90 }^{ \circ  }$.

Angles which measure $ {0}^{o} $ and less than $ {90}^{o} $ are acute angles.

Angles between $ {90}^{o} $ and $ {180}^{o} $ are obtuse angles.

Hence, $ {179}^{o} $ is an obtuse angle.

An angle which measures $ {180}^{o} $ is called a straight angle.

An angle which measures $180^o$ is called a straight angle

An acute triangle has three acute angles (utmost). An obtuse (or right) triangle has two acute angles. A triangle has at least two acute angles.

angles greater than 0 degree and less than 90 degrees are known as acute angles..

obtuse angles are those angles which are greater than 90 degrees and less than 180 degrees..

an angle which measures 180 degrees is calles straight angle..

angles greater than 90 degrees and less than 180 degrees are known as obtuse angles..

an angle which measures more than 0 degree and less than 90 degree is called an acute angle..

Right angle measures $\displaystyle  { 90 }^{ o }$
$\displaystyle  { 1 }^{ o }$ less of right angle = $\displaystyle { 90 }^{ o }-{ 1 }^{ o }$
$\displaystyle { 89 }^{ o }$
Which is an acute angle.

Acute angle is the angle which is greater than $\displaystyle { 0 }^{ o }$ and less than $\displaystyle { 90 }^{ o }$.

Let one angle is $\displaystyle { 30 }^{ o }$ and the other angle is $\displaystyle { 40 }^{ o }$ then sum $\displaystyle { 70 }^{ o }$. which is an acute angle.
Let one angle be $\displaystyle { 70 }^{ o }$ and other angle is $\displaystyle { 80 }^{ o }$, then sum is $\displaystyle { 150 }^{ o }$ which is obtuse angle.
Let one angle is $\displaystyle { 45 }^{ o }$ and another angle is $\displaystyle { 45 }^{ o }$ then sum is $\displaystyle { 90 }^{ o }$ which is right angle.

Right angle $=90^{\circ}$

Acute angle is the angle which is greater than $\displaystyle { 0 }^{ o }$ and less than $\displaystyle { 90 }^{ o }$.

A straight angle can be formed when the hour and minute hands becomes $180^0$ and that happens at $12:30$

An angle which measures more than $90^o$ but less than $180^o$ is called as an obtuse angle.

Acute angles are angles whose measurements fall between 0 and 90 degrees.

An angle that measures $<180^o$ but $>90^o$ is called an obtuse angle.

An angle of measure $180^o$ is called a straight  angle. [ Using definition of the straight angle]

Angle formed by straight angle $=180^o$

Measure of obtuse angle

An angle which measure more than $0^o$ and less than $90^o$ is an acute angle.

An straight angle always makes an angle of $ 180^o $.

An angle which measure $0^0$ is called zero angle.