A triangle has angles 80, (7x -1) and (6x -3) degrees. What is the value of x?

2 Answers
Jan 11, 2018

x=8

Explanation:

• " the sum of the 3 angles in a triangle "=180^@

"thus the 3 given angles sum to 180"

rArr80+7x-1+6x-3=180

rArr13x+76=180

"subtract 76 from both sides"

13xcancel(+76)cancel(-76)=180-76

rArr13x=104

"divide both sides by 13"

(cancel(13) x)/cancel(13)=104/13

rArrx=8

rArr7x-1=(7xx8)-1=55

rArr6x-3=(6xx8)-3=45

"the angles are "80^@,55^@" and "45^@

color(blue)"As a check"

80+55+45=180

Jan 11, 2018

x = 8

Explanation:

Angle sum property of the DeltaABC (say),

/_A +/_B + /_C = 180^@

:. 80 + 7x - 1+ 6x - 3 = 180

13x + 76 = 180

13x = 104

x = 104/13

x = 8

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