Introduction
This STEP support module includes some work on trigonometric inequalities and using them to solve equations, and a "proof" that all triangles are isosceles. Previous assignments can be found here, but you can do this one without having done the others first.
STEP questions are difficult, they are supposed to be and you should expect to get stuck. However, as you tackle more and more STEP questions you will develop a range of problem solving skills (and spend less time "being stuck").
About this assignment
The assignment is published as a pdf file below. Each STEP Support assignment module starts with a warm-up exercise, followed by preparatory work leading to a STEP question. Finally, there is a warm-down exercise.
The warm up for this assignment has some questions about functions.
The main STEP question (2015 STEP 1 Question 2) involves a cubic equation which you can solve by using trigonometric identities.
The final question seems to show you a proof that all triangles are isosceles. There is a flaw for you to find!
For more on cubic equations see this Plus maths article.
Hints, support and self evaluation
The “Hints and partial solutions for Assignment 16” file gives suggestions on how you can tackle the questions, and some common pitfalls to avoid, as well as some partial solutions and answers.
Here is a Worked Video Solution to the STEP question from this assignment.