Here is trapezium ABCD - Edexcel - GCSE Maths - Question 19 - 2021 - Paper 1
Question 19
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=21×(Base1+Base2)×Height\nPlugging in the known values, we have:\n66=21×(2x+3x)×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°)=6h\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=21×(5x)×3\nSimplifying gives us:\n66=215x\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} ).