Question

Triangles and algebra

Answer 1

Hello from MrBillDoesMath!

Answer:

x = 10

Discussion:

A plane triangle contains 180 degrees. Adding the angles in the triangle shown in  #8 gives

(4x + 7) + (3x + 13) + 90 = 180

Note the "right angle" shown in the triangle has been replaced by its 90 degree equivalent in the above equation.

Combining like terms gives

( 4x + 3x) + (7 + 13) + 90 = 180

7x + 20 + 90 = 180 =>                      (subtract 90 from each side)

7x + 20 + 90 - 90 = 180 - 90 = 90  =>

7x +20 = 90  =>                                (subtract 20 from each side)

7x + 20 -20 = 90 -20 =>

7x = 70 =>

x 70/7 =10.

Thank you,

MrB