SME
Grade 10 Math · Geometry
Geometry basics: points, lines, segments, angles and constructions
Use this for “B is between A and C, AB = 4.5 cm and BC = 7 cm. Find AC” with the segment addition postulate.
Diagram
AC = 11.5 cm
This is an example. Type your own values to start a new problem.
AC (cm)
=
AB (cm)
+
BC (cm)
Formulas
AC = AB + BC
11.5 = 4.5 + 7
Assumptions
•
B is on segment AC, between A and C.
•
Then the two parts add to the whole: AB + BC = AC (the Segment Addition Postulate).
•
Lengths add only along one line: with B off the line, AB + BC is more than AC.
Step-by-step
WE KNOW
AB = 4.5 cm, BC = 7 cm
FIND
AC (AC)
Step 1 · Find AC (AC)
Use AC = AB + BC
The two parts of the segment add to the whole.
AC = 4.5 + 7
AC = 11.5 cm
Check
Put the numbers back in. Both sides should match.
11.5 = 4.5 + 7 ✓
Topic check
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