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Literal Equations and Rearranging Formulae — Free MYP5 Mathematics (Standard) Practice Questions
1QuestionRearranging with Fractions and BracketsAssessment Practice
2 marks~3 minCriterion A
A surveyor models a triangular plot of land. The three sides measure a=5 m, b=7 m, and c=6 m, where angle θ is opposite side c. The cosine rule states:
c2=a2+b2−2abcosθ
a
Rearrange the cosine rule to make cosθ the subject. [1]
b
Calculate θ and hence justify whether the triangular plot contains any obtuse angle. [1]
Solutions
2QuestionCommon Mistakes in RearrangingAssessment Practice
2 marks~3 minCriterion C
A landscape architect is designing a triangular garden bed. The area must be exactly 30m2 and the base measures 6m.
To find the required height h, a student rearranges A=21bh and writes:
h=21×30×6
a
Identify the error in the student's rearrangement. [1]
b
Deduce the correct value of h. [1]
Solutions
3QuestionApplications in Geometry and Physics FormulasAssessment Practice
4 marks~6 minCriterion D
A photographer uses a thin lens with a focal length of f=50 mm. The lens formula
f1=u1+v1
relates object distance u and image distance v.
a
Show that v=u−fuf. [1]
b
An object is placed at u=200 mm from the lens. Calculate the image distance v. [1]
c
A sharp image requires v to fall within 2 mm of the calculated value. Assess whether the thin-lens model is reliable enough to guarantee this precision for a professional camera lens, justifying your answer with two distinct physical limitations of the model. [2]
Solutions
4QuestionApplications in Geometry and Physics FormulasAssessment Practice
4 marks~6 minCriterion B
A construction team is checking whether a triangular brace is truly right-angled before installing it. They measure the three sides as 2.5 m, 6 m, and 6.5 m.
Before applying this to the brace, investigate the relationship between side lengths in right triangles using the four Pythagorean triples below.
For each triangle, calculate the sum of the squares of the two shorter sides and the square of the longest side. [1]
b
Deduce a general equation relating the three side lengths of any right triangle. [1]
c
Using your equation from (b), advise the construction team whether the brace with sides 2.5 m, 6 m, and 6.5 m should be approved for installation, justifying your answer with full working. [2]