Flag Magical Mathematics[Interesting Approach]> Prove that : a^2sin2c + c^2 sin2A = 4∆ By...
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Prove that : a^2sin2c + c^2 sin2A = 4∆
By using tangent rule and half angels rule

Sampath sriram , 7 Years ago
Grade 11
anser 1 Answers
Arun

Last Activity: 7 Years ago

b2sin2C + c2sin2B    = b2(2sinC cosC) + c2(2sinB cosB) Since, sinC/c =sinB/b = sinA/a = R   So,  = b2(2Rc cosC) + c2(2RbcosB)   =b2[2Rc ×{b2+a2 - c2}/(2ab)]+c2[2Rb×{a2 + c2-b2}/(2ac)]   =2Rbc [ {b2+a2 - c2}/(2a) + {a2 + c2-b2}/(2a)]   =2Rbc [ a]   = 2bc(Ra)   =2bcsinA = 4 * Area of triangle ABC
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