Question

12. If the three angles of a quadrilateral are 100°, 130°, 60° then what is the fourth angle?
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Answer 1

Answer:

70 degrees

Step-by-step explanation:

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Answer 2

$\huge\bf{Answer :}$

Given :

• Three angles of quadrilateral = 100°, 130°, 60°

To find :

• Measure of fourth angle of the quadrilaterals.

Explanation :

Let the fourth angle of the quadrilateral be ∠x

As we know that,

Measure of all angles of the quadrilateral = 360°

∴ 100° + 130° + 60° + ∠x = 360° [ angle sum property ]

⇒ 290° + ∠x = 360°

⇒ ∠x = 70° ✔️

Hence, the measure of 4th angle is 70°.

Points to keep in mind :-

• A quadrilateral has four sides and four angles.
• The measure of four angles of a quadrilateral is equal to 360°. This property is known as angle sum property of the quadrillion.
• Such type of questions can be solved by applying the angle sum property and then by finding the unknown angle.

$\huge\bf{Extra\: Information :}$

• The sum of angles in a triangle is 180°.
• A triangle has three sides and three angles.
• Example of some quadrilateral : square, rectangle, rhombus, parallelogram, trapezium, etc.
• Square is considered as a special quadrilateral that has properties of almost every quadrilateral.

Properties of a square :-

• All the sides are of equal length.
• All angles have the same measure.
• Diagonals have the same length and they bisect each other at 90°.
• All angles are right angle.

Properties of Rhombus :-

• It is also considered as a Diamond. ( because of it's diamond shape. )
• Opposite angles have equal measure.
• Diagonals bisects these equal angles.
• Opposite sides are parallel to each other in a rhombus.
• Diagonals bisect each other at 90°.
• The adjacent angles have the sum equal to 180°.