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Question Number 176318 by Matica last updated on 16/Sep/22

Commented by Rasheed.Sindhi last updated on 16/Sep/22

find area of quadrilateral ABCD

findareaofquadrilateralABCD

Commented by mr W last updated on 16/Sep/22

A=((tan 45°)/4)×(8^2 +10^2 −2^2 −6^2 )=31

A=tan45°4×(82+1022262)=31

Commented by Matica last updated on 16/Sep/22

please say more detail

pleasesaymoredetail

Answered by mr W last updated on 16/Sep/22

Commented by mr W last updated on 16/Sep/22

A_1 =((ef sin θ)/2)  A_2 =((fg sin θ)/2)  A_3 =((gh sin θ)/2)  A_4 =((he sin θ)/2)  A=A_1 +A_2 +A_3 +A_4     a^2 =e^2 +f^2 −2ef cos θ  ⇒a^2 =e^2 +f^2 −((4A_1 )/(tan θ))   ...(i)  b^2 =f^2 +g^2 +2fg cos θ  ⇒b^2 =f^2 +g^2 +((4A_2 )/(tan θ))   ...(ii)  c^2 =g^2 +h^2 −2gh cos θ  ⇒c^2 =g^2 +h^2 −((4A_3 )/(tan θ))   ...(iii)  d^2 =h^2 +e^2 +2he cos θ  ⇒d^2 =h^2 +e^2 +((4A_4 )/(tan θ))   ...(iv)  (ii)+(iv)−(i)−(iii):  −a^2 −c^2 +b^2 +d^2 =((4(A_1 +A_2 +A_3 +A_4 ))/(tan θ))  ⇒A=((∣tan θ∣∣(a^2 +c^2 −b^2 −d^2 )∣)/4)      (θ≠90°)

A1=efsinθ2A2=fgsinθ2A3=ghsinθ2A4=hesinθ2A=A1+A2+A3+A4a2=e2+f22efcosθa2=e2+f24A1tanθ...(i)b2=f2+g2+2fgcosθb2=f2+g2+4A2tanθ...(ii)c2=g2+h22ghcosθc2=g2+h24A3tanθ...(iii)d2=h2+e2+2hecosθd2=h2+e2+4A4tanθ...(iv)(ii)+(iv)(i)(iii):a2c2+b2+d2=4(A1+A2+A3+A4)tanθA=tanθ∣∣(a2+c2b2d2)4(θ90°)

Commented by Matica last updated on 16/Sep/22

Thank you

Thankyou

Commented by Tawa11 last updated on 18/Sep/22

Great sir

Greatsir

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