Question

if x, 25 and 80 are angles of a triangle, find the size of x​

Answer 1

Given:

A triangle with -

• First angle = x°
• Second angle = 25°
• Third angle = 80°

What To Find:

We have to find -

• The value of x.

How To Find:

To find, we have to -

• First, form an equation using a certain property.
• Next, solve the equation.
• Finally, find the value of x.

Property Needed:

The property is -

• Sum of the interior angle = 180°

Solution:

Using the property,

⟹ Sum of the interior angle = 180°

Substitute the value of the angles,

⟹ x° + 25° + 80° = 180°

Add the angles in LHS,

⟹ x + 105 = 180

Take 105 to RHS,

⟹ x = 180 - 105

Subtract 105 from 180 in RHS,

⟹ x = 75°

Verification:

Using the property,

⟹ Sum of the interior angle = 180°

Substitute the value of the angles,

⟹ x° + 25° + 80° = 180°

Substitute the value of x,

⟹ 75° + 25° + 80° = 180°

Add the angles in LHS,

⟹ 180° = 180°

∵ LHS = RHS

∴ Hence, verified.

Final Answer:

∴ Hence, the value of x is 75°.

Answer 2

Given :

• 1st angle of triangle = x
• 2nd angle of triangle = 25°
• 3rd angle of triangle = 80°

To Find :

• Value of x

Solution :

✦ Sum of all the angles of Triangle = 180°

⠀⟶⠀Angle sum property = 180°

⠀⟶⠀x + 25° + 80° = 180°

⠀⟶⠀x + 105° = 180°

⠀⟶⠀x = 180° - 105°

⠀⟶⠀x = 75°

⛬ Value of x is 75°

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More About Triangles :

• A triangle has four vertices
• A triangle has three edges
• A triangle has three sides
• A triangle has three angles
• The sum of angle of a triangle is equal to 180⁰
• Perimeter of triangle = Sum of all sides
• Area of triangle = 1/2 × base × height
• Area of triangle (heron's formula) = √s(s- a) (s - b) (s -c)
• Semi perimeter of triangle = a+b+c/2
• Triangle is closed and 2D shape
• Equilateral triangle, scalene triangle and isosceles triangle are different types of triangles according to their sides
• Acute triangle, right triangle and obtuse triangle are different types of triangles according to their angles
• A triangle is also a polygon

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