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Hello.

I am wondering how I can find the area of a trapezoid from its two legs and bases.

My problem:

If we trace a straight line from A down parallel to the height of the trapezium, we get a right - angle triangle. From this triangle we can find the height by calculating the cosine of ∠ADC, then find the area by the Area of Trapezium formula. This should solve the problem, right?

Sources:

http://www.analyzemath.com/Geometry/trapezoid_solve.html

http://www.bbc.co.uk/schools/gcsebitesize/maths/geometry/furthertrigonometryhirev2.shtml

https://www.mathsisfun.com/sine-cosine-tangent.html

I am a high school student. Unfortunately, still did not learn anything about cos, sin and tan, but I would like to know if I am on the right path with this problem.

Thank you.

EDIT: and also, do I have to solve this using cos and trigonometry, or can I use another method if it is more simple?

I am wondering how I can find the area of a trapezoid from its two legs and bases.

My problem:

*ABCD is a trapezium with AB parallel to CD such that AB = 5, BC = 3, CD = 10 and AD = 4. What is the area of ABCD?*If we trace a straight line from A down parallel to the height of the trapezium, we get a right - angle triangle. From this triangle we can find the height by calculating the cosine of ∠ADC, then find the area by the Area of Trapezium formula. This should solve the problem, right?

Sources:

http://www.analyzemath.com/Geometry/trapezoid_solve.html

http://www.bbc.co.uk/schools/gcsebitesize/maths/geometry/furthertrigonometryhirev2.shtml

https://www.mathsisfun.com/sine-cosine-tangent.html

I am a high school student. Unfortunately, still did not learn anything about cos, sin and tan, but I would like to know if I am on the right path with this problem.

Thank you.

EDIT: and also, do I have to solve this using cos and trigonometry, or can I use another method if it is more simple?

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