Question

Find the value of unknown ange 2
ir each of following

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Answer 1

1. x = 50 + 70 ( Exterior angle is equal to the sum of interior opp. angles)

x = 120°

2. 80 = x + 30( Exterior angle is equal to the sum of interior opp. angles)

x = 80 - 30 = 50°

3. 30 + 90 + x = 180 ( Angle sum Property of Triangle)

120 + x = 180

x = 180 - 120

x = 60°

Answer 2

Answer :

$\sf(i)sum \: of \: interior \: \: angles \: of \: a \: triangle \: is = 180 \degree$

$\sf \: let \:3rd \: interior \: angle \: = y \\ \sf 50 \degree + 70 \degree + y= 180 \degree \\ \sf = 120 \degree + y = 180 \degree \\ \sf = y = 180 \degree - 120 \degree = 60 \degree$

$\sf \angle \: y \: + \angle \: x = 180 \degree(Linear \: pair \: angles) \\ \sf60 \degree + x = 180 \degree \\ \sf x= 180 \degree - 60 \degree \\ \sf = x = 120 \degree$

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$\sf(ii)sum \: of \: interior \: \: angles \: of \: a \: triangle \: is = 180 \degree$

$\sf \: let \: 3rd \: interior \: angle \: = y$

$\sf80 \degree + y = 180 \degree \sf(linear \: pair \: angles) \\ \sf = y = 180 \degree - 80 \degree \\ \sf \: y = 100 \degree$

$\sf \: now.. \\ \sf \: x + 30 \degree + y = 180 \degree \\ \sf \: x + 30 \degree + 100 \degree = 180 \degree \\ \sf = x + 130 \degree = 180 \degree \\ \sf \: x = 180 \degree - 130 \degree \\ \sf x = 50 \degree$

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$\sf(iii)sum \: of \: interior \: \: angles \: of \: a \: triangle \: is = 180 \degree$

$\sf90 \degree + 30 \degree + x = 180\degree \\ \sf120\degree + x = 180\degree \\ \sf x = 180\degree - 120\degree \\ \sf \: x = 60\degree$