Mathematics 4024 · O Level · Area and perimeter

Area and perimeter — practice question

ABCD is a trapezium with $AB$ parallel to $DC$. $DC = 15\text{ cm}$ and $AB = x\text{ cm}$. The perpendicular distance between $AB$ and $DC$ is $3\text{ cm}$ shorter than the length of $AB$. The area of $ABCD$ is $75\text{ cm}^2$.
(a(i))[2]

Show that $x^2 + 12x - 195 = 0$.

(a(ii))[3]

Calculate $AB$, giving your answer correct to $1$ decimal place.

(a(iii))[2]

Since $AD$ is $0.8\text{ cm}$ longer than $BC$, and the perimeter of the trapezium is $38.0\text{ cm}$, calculate $AD$.

(b(i))[2]

A different trapezium, $LMNO$, has $LM$ parallel to $ON$. The reflex angle $LMN = 252^\circ$. Calculate $\angle MNO$.

(b(ii))[3]

The angle ratios inside the trapezium are $\angle LON : \angle LMN = 1 : 2$ and $\angle OLM : \angle MNO = 1 : k$. Find $k$, giving your answer as a fraction in simplest form.

Worked solution & mark scheme

This 12-mark question has a full step-by-step worked solution and mark scheme. One marking point: $\frac12(x+15)(x-3)=75$

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