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Area of triangle- please help :)

Area of triangle- please help :)-example-1
User Jkyadav
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User Maths Noob
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Answer:


\approx 45.1\:\mathrm{w/\: some \: MOE}

Explanation:

The area of
ABCD is comprised of two triangles, so we can find the area of both triangles and add them to get the total area of

Since the sum of the interior angles of a triangle add up to
180^(\circ), we have:


\angle C=180-44-38=\fbox{$98^(\circ)$}.

The Law of Sines is given as:


(\sin A)/(a)=(\sin B)/(b)=(\sin C)/(c) for any triangle.

Therefore, we have the proportion:


(\sin 98^(\circ))/(10)=(\sin 44^(\circ))/(BC),\\BC=(10\cdot \sin 44^(\circ))/(\sin 98^(\circ)),\\BC\approx 7.01.

Now that we have two sides of a triangle and the angle between them, we can use
[\triangle]=(1)/(2)ab\sin C to find the area of
\triangle CBD:


[CBD]=(1)/(2)\cdot 10\cdot 7.01 \cdot \sin 38^(\circ),\\\\\left [CBD]\right\approx 21.58.

Since
\triangle ABD is a right triangle, we can use basic trig rules for a right triangle to solve for the sides:


\sin 55^(\circ)=(AB)/(10),\\AB=10\sin 55^(\circ),\\AB\approx 8.19,


\sin 35^(\circ)=(AD)/(10),\\AD=10\sin 35^(\circ),\\AD\approx 5.74.

Therefore, the area of
\triangle ABD is:


(1)/(2)\cdot 8.19\cdot 5.74\approx 23.49.

The area of
ABCD is then


21.58+23.49=45.07=\fbox{$45.1$}.


\bigstar Note that intermediate results were rounded during this calculation. Therefore, there is a small margin of error when rounding to final answer to one decimal place. I recommend plugging in values for yourself using all equations I wrote above, then rounding only your final answer to one decimal place as requested by the problem.