This Excellent Mathematics Learner’s Book for Grades 10 –11 has been planned and designed to prepare learners for the Namibia Senior Secondary Certificate Ordinary (NSSCO) level Mathematics examination at the end of Grade 11. The approach followed in the planning and design of this Learner’s Book is based on the following assumptions: • Mathematics is a language that enables individuals to understand and interpret the world around them. • All learners should study Mathematics in order to prepare them to participate meaningfully in an environment dominated by science and technology. • Mastering Mathematics requires a secure environment in which learners can, without any fear or anxiety discover, understand and enjoy mathematics. • Quality control by means of continuous assessment is an integral part of teaching and learning. • Detailed explanation of concepts, followed by properly worked examples and sample opportunities for practice is essential for successful teaching and learning. The work in the book is divided into the twelve topics included in the prescribed syllabus. Topics are divided into units relating to the content included in the syllabus. Each topic is concluded by a summary of the work done in the topic and an end-oftopic test. These summaries and tests will help learners to revise the work included in the topic and to monitor their own progress. It is important to remember that as both mathematical concepts and skills build on one another, a lack of understanding in a particular concept may obstruct progress in successive concepts. Both teachers and learners should be aware to make sure that proper foundations are laid before new work is introduced. The exercises in the learners’ book are designed in such way that the level of demand for some is at an advanced stage. The level of demand for all the exercises in the book under the heading: ‘Advanced’ is more than the level of demand for other exercises in the book. It is one of the requirements from the ministry that differentiation in terms of the level of demand be considered. All learners are expected to work on all the exercises in the book including the exercises at an advanced stage. The publisher and the authors of Excellent Mathematics Grades 10–11 wish leaners and teachers well. We believe that this Learner’s Book will guide you on a happy and successful journey to discover and conquer Mathematics in the Senior Secondary School Phase.