Question

3. The measures of angles of a triangle are x°,(x-20), (x-40)
Find the measure of each angle.
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Answer 1

Given :-

• Measure of 1st angle :- x°
• Measure of 2nd angle :- x -20°
• Measure of 3rd angle :- x - 40°

We know that sum of three angles of a triangle is 180°

So, simply we will add up all the angles and equal to 180.

We will get the value of x

Then, simply we can subsitute values

→ x + x - 20 + x - 40 = 180

→ x + x + x - 20 - 40 = 180

→ 3x -60 = 180

→ 3x = 180 + 60

→ 3x = 240

→ x = 240/3

→ x = 80

Thus, we got the value of x i.e 80

Subsituting Values :-

• Measure of 1st angle = x = 80°
• Measure of 2nd angle = x - 20 = 80 - 20 = 60°
• Measure of 3rd angle = x - 40 = 80 - 40 = 40°

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Answer 2

Answer :-

Given :-

3 angles of triangle :- x° , (x-20)° and (x-40)°

To find :-

Measure of each angle

Solution

$\sf x + x - 20 + x - 40 = 180\degree$ ( by angle sum property of triangle)

$\sf 3x - 20 - 40 = 180$

$\sf 3x - 60 = 180$

$\sf 3x = 180 + 60$

$\sf 3x = 240$

$\sf x = \frac{\cancel 240}{\cancel 3}$

$\sf x = 80\degree$

Angles of triangle :-

$\sf x = 80\degree$

$\sf x - 20 = 80 - 20 = 60\degree$

$\sf x - 40 = 80 - 40 = 40\degree$

Angles of traingle = 80° , 60° and 40°.