Question

Look at the figure given below. State for each triangle whether it is acute, obtuse or right.

Answer 1

Classifying the triangle as acute, obtuse or right triangle:

From the figure,

Two angles of the triangle are acute angles i.e., $40°and35°$

According to angle sum property ,sum of all the interior angles of a triangle $=$ $180°$

Let the third unknown angle be $x$

$40°+35°+x=180°$

$$\begin{gathered} \Rightarrow 75°+x=180° \\ \Rightarrow x=180°-75° \\ \Rightarrow x=105° \end{gathered}$$

As the third angle is greater than $90°$, so third angle in obtuse angle.

Hence, the given triangle is obtuse angled triangle as one of the angle is obtuse.