Answer:
An obtuse triangle has two angles 45 and 18. The value of the unknown angle is

Solution:
Given that two angles of an obtuse triangle is 45 and 18.
Third angle is θ
We are asked to find the value of third unknown angle theta
According to angle sum property of triangle, sum of three angles of triangle is

This means in our case sum of 45, 18 and θ should be


Hence value of unknown third angle of an obtuse triangle is