Question

sum and difference of two angles of a triangle are 80 degrees and 20 degrees respectively then the third angle is​

Answer 1

Answer:

100°

Step-by-step explanation:

Let two angles be x° and y° .

Given, x° + y = 80°

           x° - y° = 20°

Now, add both the equations ( left side with left  and right side with right)

we get, 2x° = 100°

or x = 50°

put this value of x back in first equation,

hence 50° + y°= 80°

or, y = 80° - 50° = 30°

So, both angles are  50° and 30°

So, the third angle is 180° - (50° + 30°)  = 180° - 80° = 100°

So, the third angle is 100°.

Answer 2

Answer:

Step-by-step explanation:

Let two angles be x° and y° .

Given, x° + y = 80°

          x° - y° = 20°

Now, add both the equations ( left side with left  and right side with right)

we get, 2x° = 100°

or x = 50°

put this value of x back in first equation,

hence 50° + y°= 80°

or, y = 80° - 50° = 30°

So, both angles are  50° and 30°