Find missing angles (straight line, corner, crossing lines)

Answer Key - Grade 7 Math Worksheet - Building Confidence

Circle the best answer, or write your answer on the line.

1. 1.

   Ari leans a ladder on the flat ground to rescue a kite from a tree. The ladder makes a 68° angle with the ground. What is angle x on the other side, in degrees?

   112
2. 2.

   Bo props the classroom door open for a breeze, and one curious bee flies in. The door makes a 122° angle with the straight wall. What is angle x on the other side, in degrees?

   58
3. 3.

   Luz draws a line from the square corner of a sheet of paper for a fold-it-yourself project. One part of the corner is 58°. What is the other part, angle x, in degrees?

   32
4. 4.

   Noah runs a strip of tape out from the square corner of a box flap (the cat is very interested). One part of the corner is 71°. What is angle x, in degrees?

   19
5. 5.

   Pia opens a pair of craft scissors, and the blades cross like an X. One angle between the blades is 42°. What is angle x, next to it, in degrees?

   138
6. 6.

   Ren ties two straight kite sticks so they cross. One angle between the sticks is 103°. What is angle x, next to it on the same stick, in degrees?

   77
7. 7.

   Zee leans one pencil against another pencil lying flat on the desk, like a tiny ramp. The angles on each side are 125° and x. What kind of angle pair are they?

   • Vertical angles: they are equal
   • Complementary angles: they add to 90°, like a square corner
   • Supplementary angles: they add to 180°
8. 8.

   Bo's ladder leans on flat ground by the apple tree. The angles on each side of the ladder are 72° and x. What kind of angle pair are they?

   • Supplementary angles: they add to 180°
   • Complementary angles: they add to 90°
   • Vertical angles: they are equal
9. 9.

   Jun's bike stands on its kickstand on flat ground. The kickstand makes a 57° angle with the ground, and angle x is on the other side. Which equation finds x?

   • x + 57 = 360
   • x = 57
   • x + 57 = 180
   • x + 57 = 90
10. 10.

    Kira pushes the art-room door open (paint smell included). The door makes a 139° angle with the straight wall, and angle x is on the other side. Which equation finds x?

    • x = 139
    • x + 139 = 360
    • x + 139 = 90
    • x + 139 = 180