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7th grade Find missing angles (straight line, corner, crossing lines) worksheet

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

Grade 7 Math Worksheet - Building Confidence

NameDate

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

  1. Kira sews a straight stitch line out from the square corner of a quilt patch. One part of the corner is 27°. What is the other part, angle x, in degrees?

  2. 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?

  3. 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?

  4. 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?

  5. 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?

  6. On Tala's town map, two straight streets cross by the library. One angle at the crossing is 64°. What is angle x, next to it along the same street, in degrees?

  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?

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

  8. Esme cuts a straight line from the square corner of a paper square for a pinwheel. It splits the corner into a 16° angle and angle x. What kind of angle pair are they?

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

  9. 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 = 90
    • x + 139 = 360
    • x = 139
    • x + 139 = 180

  10. Milo's safety scissors cross like an X while cutting out a paper crown. Angle x is across from a 47° angle. Which equation finds x?

    • x = 47
    • x + 47 = 360
    • x + 47 = 180
    • x + 47 = 90
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7th grade Find missing angles (straight line, corner, crossing lines) worksheet – printable
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About this worksheet

Find missing angles (straight line, corner, crossing lines). Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

  • I can find a missing angle on a straight line (180°), in a square corner (90°), all the way around a point (360°), in a triangle (180°) and where two or three lines cross.
  • I can name a pair of angles: supplementary (add to 180°), complementary (add to 90°), vertical (across, so equal).
  • I can write an equation for an unknown angle, like 3x + 17 + 19 = 90, solve it, and find the angle.

Standard: 7.G.B.5

Words to know

ray: A straight line that starts at a point and goes on in one direction.

straight line: A line with no bend. The angles along it at one point add to 180°.

square corner (right angle): A corner like a page's corner, 90°, marked with a small square.

adjacent angles: Two angles side by side, sharing a corner point and one side.

supplementary angles: Two angles that add to 180°, like the two parts of a straight line.

complementary angles: Two angles that add to 90°, like the two parts of a square corner.

vertical angles: Angles across from each other where two lines cross. They are equal.

unknown angle: An angle we don't know yet, written with x, like (2x + 9)°.

Common mistakes

Your child used 90° for angles on a straight line (180°), or 180° for angles in a square corner (90°).

Your child used 360°, a full turn around a point, for angles that only make a straight line (180°), a square corner (90°) or a triangle (180°), or for two vertical angles, which are simply equal.

Your child mixed up angles across from each other at a crossing (they are equal) with angles side by side on a line (they add to 180°). Try: cross two pencils and point to the angle across from each one.

What to say

Ask: is this a straight line or a square corner?

Ask: do these angles go all the way around the point?

Questions parents ask

What is the most common mistake with find missing angles (straight line, corner, crossing lines)?

Your child used 90° for angles on a straight line (180°), or 180° for angles in a square corner (90°).

How can I help my child with find missing angles (straight line, corner, crossing lines)?

Ask: is this a straight line or a square corner?

Are these 7th grade math worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

More grade 7 math

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