For Geometry lovers, help me solve this?

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1 Answer
CW · P dilip_k
Feb 15, 2018

Area #52.102 " cm"^2#

Explanation:

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#angleAOB=alpha=360^@/5=72^@#
Area of #DeltaOAB=A_1=1/2*7^2*sinalpha=1/2*49*sin72=23.3009 " cm"^2#
#tanalpha=(AT)/(OA)#,
#=> AT=OA*tan72=7*tan72=21.5438# cm
Area of #DeltaOAT=A_2=1/2*OA*AT=1/2*7*21.5438=75.4033 " cm"^2#
#=># Area of #DeltaABT="shaded area"=A_2-A_1=75.4033-23.3009~~52.102 " cm"^@#

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