Should I take lessons?

I'm a pretty musical guy. I'm in 11th grade, I've been playing guitar for about 10 years, I started playing trumpet last year and oboe this year. I want to learn all the instruments I can possibly learn, for both composition purposes and for fun.

My next mission is the Viola (which I personally find to be the most awesomest instrument of the string section by about a thousand points). The thing is I'd rather not take lessons from a private teacher, for money reasons. My question is, should I just wing it and buy a "Viola for Dummies" book or something, or are there some things which are absolutely necessary to learn from a living human being teacher? Keep in mind that while I have expirience with learning instruments, I have almost none with bowed string instruments.

Should I take lessons?

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