Question

The three angles of a quadrilateral are 60 80 and 100 what is the fourth angle ?

Answer 1

Answer:

120 degrees

Step-by-step explanation:

the total sum of all angles of a quadrilateral is 360.

∴60+80+100+∠4=360

⇒240+∠4=360

∴∠4=120 degrees

Answer 2

ANSWER:

120°

Step-by-step explanation:

The total sum of all angles in any quadrilateral is 360°.

It is given that the three angles of a quadrilateral are 60°, 80°, and 100°. Let these three angles be a,b and c respectively.

Therefore, let the unknown angle be d.

$a + b + c + d = 360 \\ 60 + 80 + 100 + d = 360 \\ 240 + d = 360 \\ d = 360 - 240 \\ d = 120$

ADDITIONAL INFORMATION:

For verification,

let d be 120°, as per our answer, hence:

$a + b + c + d = 360 \\ 60 + 80 + 100 + 120 = 360 \\ 140 + 100 + 120 = 360 \\ 240 + 120 = 360 \\ 360 = 360 \\ hence \: proved$