MathAmigo

Basic Geometry

Secondary 1 practice

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Basic Geometry practice questions

Secondary 1 topics, the foundation the O-Level Mathematics 4052 syllabus builds on. Every question below has a full worked solution.

When a student gets a question wrong in Math Amigo, it does not show the answer straight away. It reads the working, identifies the step that went wrong, and asks a question that points at the correction. The worked solution is there once a genuine attempt has been made.

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What this topic covers

Worked examples

Example 1

One supplementary angle is 55 times the other. Find the smaller angle.
Show the worked solution
  • Let the smaller angle be x\text{Let the smaller angle be } x
  • x+5x=180°(supplementary ∠s)x + 5x = 180° \quad (\text{supplementary } \angle\text{s})
  • 6x=180°6x = 180°
  • x=1806x = \frac{180}{6}
  • =30°= 30°

Answer: 3030

Example 2

Three angles on a straight line are 77°77°, 47°47° and y°y°. Find yy.
77°47°yNot drawn to scale
Show the worked solution
  • 77+47+y=180(adj. ∠s on a str. line)77 + 47 + y = 180 \quad (\text{adj. } \angle\text{s on a str. line})
  • 124+y=180124 + y = 180
  • y=180−124y = 180 - 124
  • =56= 56

Answer: 5656

Example 3

Two straight lines AB and CD intersect at O. ∠AOC=50°\angle AOC = 50°. OE bisects ∠BOD\angle BOD. Find ∠DOE\angle DOE.
BACDE50°?ONot drawn to scale
Show the worked solution
  • ∠BOD=∠AOC=50°(vert. opp. ∠s)\angle BOD = \angle AOC = 50° \quad (\text{vert. opp. } \angle\text{s})
  • ∠DOE=50°2(OE bisects ∠BOD)\angle DOE = \frac{50°}{2} \quad (\text{OE bisects } \angle BOD)
  • =25°= 25°

Answer: 2525

Questions parents ask

Is it really free?

The free plan is permanent and does not ask for a card. It has daily limits on the AI feedback, and the paid plans lift them.

Which syllabus does this follow?

O-Level Mathematics (4052), for Singapore secondary students. Math Amigo covers Secondary 1 to 4, both O-Level Mathematics and Additional Mathematics.

Will it just show my child the answer?

No. On a wrong answer it looks at the working, points to the step that went wrong, and asks a question that helps the student find the correction. The full worked solution is available after a genuine attempt.

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