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How to do question 22?

How to do question 22?-example-1
User Bobelev
by
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1 Answer

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Answer:

A = 20sinθ(6 + 5 cosθ) cm²

Explanation:

Drop perpendiculars DE and CF to AB.

Then, we have congruent triangles ADE and BCF, plus the rectangle CDEF.

The formula for the area of the trapezium is

A = ½(a + b)h

DE = 10sinθ

AE = 10cosθ

BF = 10cosθ

EF = CD = 12 cm

AB = AE + EF + BF = 10cosθ + 12 + 10 cosθ = 12 + 20cosθ

A = ½(a + b)h

= ½(12 +12 + 20 cosθ) × 10 sinθ

=(24 + 20 cosθ) × 5 sinθ

= 4(6 + 5cosθ) × 5sinθ

= 20sinθ(6 + 5 cosθ) cm²

How to do question 22?-example-1
User Srikanth Rongali
by
8.7k points

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