Dr. Sanjeev Verma and R.K. Tyagi Solutions for Chapter: Understanding Elementary Shapes, Exercise 4: ASSIGNMENT 6.4

Two angles of a triangle measure $78°$ and $36°$.the measure of the third angle is.

In the adjoining figure, the measures of various angles are indicated. Find the values of $x$ and $y$ respectively.

 Which of the following can be the possible lengths (in $\mathrm{cm}$ ) of a triangle ? 
 $21,22,43$

 Study the $9$ triangles in the following figure:
 Name the obtuse triangles.

 Study the $9$ triangles in the following figure:
 Name the acute triangles.

O is a point in the interior of $∆\mathrm{ABC}$. State which of the following statements are true or false. Give reasons in support of your answer.
$\mathrm{OA}+\mathrm{OB}>\mathrm{AB}$
 

 O is a point in the interior of $∆\mathrm{ABC}$. State which of the following statements are true or false. Give reasons in support of your answer.
$\mathrm{OB}+\mathrm{OC}>\mathrm{BC}$
 

O is a point in the interior of $∆\mathrm{ABC}$. State which of the following statements are true or false. Give reasons in support of your answer.

$\mathrm{OA}+\mathrm{OC}=\mathrm{AC}$