https://img707.imageshack.us/img707/121/6878.png
A(ABD)=A(ADC) |AD|=a olsun. A(ABD)=(4.a.sinx)/2 A(ADC)=(8.a.sin2x)/2 sinx=2.sin2x sinx=2.2.sinx.cosx cosx=1/4
teşekkürler hocam