Answer:
∠?=40°
Step-by-step explanation:
Remember that in a line AND a triangle there are 180 degrees.
You correctly found the third angle in the left triangle to be 69°, Now plug it into the equation for a line, including 71°:
69°+71°+x=180°
1) Combine the degrees:
140°+x=180°
2) Subtract 140° from both sides:
x=40°
We have now found the bottom left angle for the triangle on the right to be 40°
To find the angle labeled "?" You must plug in all of the known angles of the triangle to be equal to 180°:
40°+100°+x=180°
1) Combine the degrees:
140°+x=180°
2) Subtract 140 from both sides:
∠?=40°
