# Homework Help: Makes no sense as theta is obviously obtuse

1. Jul 8, 2012

### synkk

Working for a)

Resolving upwards:

12cos(θ -90) - 8 = 0
cos(θ-90) = sinθ
12sinθ = 8
sinθ = 2/3
θ = 41.8 (3.sf)

This makes no sense as theta is obviously obtuse, if I don't simplify to sinθ I get:

cos(θ-90) = 2/3
θ = 48.2... + 90
= 138.2 (1.dp)

Why does it not work if I simplify to sinθ?

2. Jul 8, 2012

### Villyer

Re: Statics

sinθ = 2/3 has an infinite number of solutions, what are some others?

3. Jul 8, 2012

### synkk

Re: Statics

180 - θ

silly me, thanks.