Area of CDE = 1/3of area of AGD ?
84×3= AGD
AGD=252
Where I am wrong ?
Right here
area of CDE = \frac{CE * DE}{2}
area of AGD = \frac{AG * DG}{2} = \frac{3CE * 3DE}{2} = 9 * \frac{CE * DE}{2} = 9 * area CDE
This is not true.
They are similar triangles. Their sides are in proportion.
We can’t directly say that CDE is 1/3rd AGD.
So, from concept of similarity, AG = 3 * CE, DG = 3 * DE.
0.5 * CE * DE = 42
So, 0.5 * AG * DE = 9*42 = 378.