Copying an angle
Draw ∠PQR = 35° with a protractor. Then, with a compass, construct ∠CAB equal to it at A.
Draw ∠PQR = 50° with a protractor. Then, with a compass, construct ∠CAB equal to it at A.
Draw ∠PQR = 95° with a protractor. Then, with a compass, construct ∠CAB equal to it at A.
Draw ∠PQR = 130° with a protractor. Then, with a compass, construct ∠CAB equal to it at A.
Draw ∠PQR = 160° with a protractor. Then, with a compass, construct ∠CAB equal to it at A.
1. Draw ∠PQR = 35° with a protractor.
2. Draw a line AB below it.
3. With Q as the center and any radius, draw an arc that cuts QR at D and QP at E.
4. With A as the center and the same radius, draw an arc that cuts AB at X.
5. Open the compass to DE. With X as the center and that radius, cut the arc at Y.
6. Join AY and produce it to C: ∠CAB = ∠PQR = 35°.
1. Draw ∠PQR = 50° with a protractor.
2. Draw a line AB below it.
3. With Q as the center and any radius, draw an arc that cuts QR at D and QP at E.
4. With A as the center and the same radius, draw an arc that cuts AB at X.
5. Open the compass to DE. With X as the center and that radius, cut the arc at Y.
6. Join AY and produce it to C: ∠CAB = ∠PQR = 50°.
1. Draw ∠PQR = 95° with a protractor.
2. Draw a line AB below it.
3. With Q as the center and any radius, draw an arc that cuts QR at D and QP at E.
4. With A as the center and the same radius, draw an arc that cuts AB at X.
5. Open the compass to DE. With X as the center and that radius, cut the arc at Y.
6. Join AY and produce it to C: ∠CAB = ∠PQR = 95°.
1. Draw ∠PQR = 130° with a protractor.
2. Draw a line AB below it.
3. With Q as the center and any radius, draw an arc that cuts QR at D and QP at E.
4. With A as the center and the same radius, draw an arc that cuts AB at X.
5. Open the compass to DE. With X as the center and that radius, cut the arc at Y.
6. Join AY and produce it to C: ∠CAB = ∠PQR = 130°.
1. Draw ∠PQR = 160° with a protractor.
2. Draw a line AB below it.
3. With Q as the center and any radius, draw an arc that cuts QR at D and QP at E.
4. With A as the center and the same radius, draw an arc that cuts AB at X.
5. Open the compass to DE. With X as the center and that radius, cut the arc at Y.
6. Join AY and produce it to C: ∠CAB = ∠PQR = 160°.
Why it works
QD = QE = AX = AY (one radius) and DE = XY (the chord carried across), so △QDE and △AXY are congruent (SSS). Their angles at Q and A are equal: ∠CAB = ∠PQR.