Secondary 2 topics, working towards the O-Level Mathematics 4052 syllabus. 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.
Isosceles △TUV has TU=TV=17 cm and UV=30 cm. TH is the perpendicular from T to UV, where H is the midpoint of UV. Find the length of TH.
Show the worked solution
Since △TUV is isosceles and TH⊥UV,H is the midpoint of UV
UH=2UV=230=15 cm
In △TUH, ∠THU=90°
TU2=TH2+UH2Pythagoras’ theorem
172=TH2+152
TH2=172−152
TH2=289−225
TH2=64
Answer: 8
Example 2
Two vertical buildings are 12 m and 28 m tall and are 30 m apart on level ground. A cable connects the tops of the two buildings. Find the length of the cable.
Show the worked solution
Vertical difference=28−12
=16 m
The cable forms the hypotenuse of a right-angled triangle with legs 16 m and 30 m.
Let the cable length=c m
c2=162+302Pythagoras’ theorem
c2=256+900
c2=1156
c=34 m
Answer: 34
Example 3
△MNP has MP=26 cm, NP=24 cm and MN=10 cm. Show that △MNP is right-angled and find its area.
Show the worked solution
Arrange the sides in order: 10,24,26
The longest side is MP=26 cm
MP2=262
=676
MN2+NP2=102+242
=100+576
=676
Since MP2=MN2+NP2,△MNP is right-angled.converse of Pythagoras’ theorem
Answer: 120
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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.