An obtuse triangle is a triangle that has one obtuse angle (greater than degrees and less than degrees) and two acute angles (each of which is less than degrees). The sum of all three angles together is degrees.
An obtuse triangle is a triangle that has one obtuse angle (greater than degrees and less than degrees) and two acute angles (each of which is less than degrees). The sum of all three angles together is degrees.
Calculate the size of angle X given that the triangle is equilateral.
Next, we will look at some examples of obtuse triangles:
Homework:
Calculate which is larger
Given that the triangle is an obtuse triangle.
Which angle is larger or ?
Solution:
Since we are given that the triangle is an obtuse triangle, we understand that is not greater than .
In a triangle, there is only one obtuse angle therefore the answer is:
Answer:
Is the triangle in the drawing an acute-angled triangle?
Is the triangle in the drawing an acute-angled triangle?
Is the triangle in the drawing an acute-angled triangle?
Given the triangle .
is obtuse.
The sum of the acute angles in the triangle is equal to .
Find the value of angle .
Solution:
Since we know that is obtuse, we are certain that angles and are acute.
This means that we have the information that the sum of the acute angles
The sum of the angles in a triangle is equal to .
Answer:
Given the obtuse triangle .
,
Task:
Is it possible to calculate ?
If so, calculate it.
Solution:
Given that:
We substitute:
Answer: yes, .
Is the triangle in the diagram isosceles?
Is the triangle in the drawing an acute-angled triangle?
Is the triangle in the drawing an acute-angled triangle?
Assignment
Which triangle is given in the drawing?
Solution
Since angles and : are both equal to , we know that the opposite sides are also equal, therefore the triangle is isosceles.
Answer
Isosceles triangle
Assignment
Determine which of the following triangles is obtuse, which is acute, and which is right:
Solution
Let's observe triangle and check if it satisfies the Pythagorean theorem, therefore we replace the data we have:
We solve the equation
The sum of the squares of the "perpendicular" is greater than the square of the rest, therefore the triangle is an isosceles triangle.
Let's observe triangle and check if it satisfies the Pythagorean theorem, therefore we replace the data we have:
We solve the equation
The sum of the squares of the "perpendicular" is less than the square of the other, therefore the triangle is obtuse
Let's observe triangle and check if the Pythagorean theorem is satisfied, first we calculate what is the square root of
This is the largest side among the: and we will refer to it as "hypotenuse".
Now we replace the data we have:
We solve the equation
In this triangle, the Pythagorean theorem is satisfied and therefore the triangle is right.
Answer
A: acute angle B: obtuse angle C: right angle
Is the triangle in the drawing an acute-angled triangle?
Is the triangle in the diagram isosceles?
Is the triangle in the drawing an acute-angled triangle?