You are Here: Home >< Maths

# trigonometyr functions and equations watch

1. https://imgur.com/a/3MX2l

i need help with the question in this link
i dont understand part b and c
2. Idk which bit of b and c you specified so I'll just explain each bit.

iii) and c

4tan4xsin4x = 15

Let's think of this as tan x, and sin x, and find those roots

express tan x as sin x/cos x, multiply through by sin x to get 4sin^2x/cos x = 15, multiply through by cos x and use the sin^2 + cos^2 = 1 identity specific to this situation, you should obtain a disguised quadratic in cos x, the same quadratic you solved, the only thing left now is to divide your roots by 4, as this is 4x.

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: March 12, 2018
Today on TSR

### AQA Mechanics Unofficial Markscheme

Find out how you've done here

### 3,084

students online now

Exam discussions

Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams