THIS BOOK IS WRITTEN BY MR. RD SHARMA .THIS BOOK IS VERY HIGHLY REVIVED BY MR. RD SHARMA .IN THIS BOOK THE FORMULAE AND CONCEPT OF MATHEMATICS ARE DESCRIBED IN SUCH A WAY THAT THE READERS OF THIS BOOK ARE VERY HAPPY . IN THIS BOOK TRIGNOMETERY AND ALL THINGS ARE VERY HIGHLY AND SIMPLY DESCRIBED .THE STUDENT OF 10 CLASS ARE VERY SEROUS ABOUT THIS BOOK . THE PRICE OF THIS BOOK IS VERY AFFORDABLE 250RS . I RECOMMENDED YOU TO BUY AND READ THIS BOOK.