Vaishali Bhatia and Rupesh Pathak Solutions for Chapter: Triangles, Exercise 8: Understand and Solve 1

Stella aunty decided to prepare a cake for her son's birthday. She chose a recipe which included baking with the following ingredients: 

$200 \mathrm{g}$ sugar, $150 \mathrm{g}$ flour, $150 \mathrm{g}$ butter, $100 \mathrm{g}$ milk, $3$ eggs, $5 \mathrm{g}$ baking soda and $1$ teaspoon essence. 

Stella's aunty drew four lines with fruit jam on the cake as shown above. Find the sum of interior angles of all the $4$ triangles formed on the cake?