i have a doubt in the chapter which is not mentioned here so may the chapter i have selected is wrong that is one of the appendex at last pages on topic proof in maths and i have to make an activity in my activity copy and i have to explain it so please help me out this is the pdf link
https://www.ncert.nic.in/ncerts/l/iemh1a1.pdf
please see this and explain me what is it?