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Here is trapezium ABCD - Edexcel - GCSE Maths - Question 19 - 2021 - Paper 1

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Question 19

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Here is trapezium ABCD. The area of the trapezium is 66 cm² The length of AB: the length of CD = 2:3 Find the length of AB.

Worked Solution & Example Answer:Here is trapezium ABCD - Edexcel - GCSE Maths - Question 19 - 2021 - Paper 1

Step 1

Find the lengths of CD and AB based on the ratio

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Answer

Let the length of CD be ( 3x ) and the length of AB be ( 2x ). Thus, the dimensions are:\n- Length of CD = 3x\n- Length of AB = 2x

Step 2

Use the area formula of the trapezium

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Answer

The area of a trapezium is given by the formula:\nArea=12×(Base1+Base2)×Height\text{Area} = \frac{1}{2} \times (\text{Base}_1 + \text{Base}_2) \times \text{Height}\nPlugging in the known values, we have:\n66=12×(2x+3x)×h66 = \frac{1}{2} \times (2x + 3x) \times h\nwhere ( h ) represents the height.

Step 3

Determine the height using trigonometric ratios

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Answer

From triangle BCD, we can use the sine function to find the height. Considering angle 30°:\nsin(30°)=h6\sin(30°) = \frac{h}{6}\nThis results in:\nh = 6 \times \sin(30°) = 6 \times \frac{1}{2} = 3 \text{ cm}.

Step 4

Substitute height back into the area formula

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Answer

Now substituting h back into the area equation, we have:\n66=12×(5x)×366 = \frac{1}{2} \times (5x) \times 3\nSimplifying gives us:\n66=15x266 = \frac{15x}{2}\nThus, multiplying both sides by 2 results in:\n( 132 = 15x ) or ( x = \frac{132}{15} = 8.8 ).

Step 5

Calculate the length of AB

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Answer

The length of AB can be found by substituting the value of x back into the equation for AB:\n( AB = 2x = 2 \times 8.8 = 17.6 \text{ cm} ).

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