If you can't grasp trigonometry by doing a quick revision on your own, I highly doubt you can 'read up' on an in-depth Physics book.
Let me give you a general introduction in a few paragraphs, if I may. Physics is colloquially categorized into Classical and Modern Physics. Modern Physics is a common term for the study of phenomena that are dealt within the Great Partial Theories of the XX century - The Theory of Relativity and Quantum Mechanics. These effects become pronounced when the objects move at speeds comparable to the speed of light in vacuo and the De Broglie wavelength associated with the particle motion becomes comparable to the linear dimensions that they traverse. In short, you can forget about this phenomena when considering an Intro to Physics.
All the previous knowledge accumulated through the preceding centuries is collected in a body called Classical Physics. The major areas of Classical Physics are:
- Classical Mechanics
- Thermodynamics and Statistical Physics
- Electromagnetism
- Optics
The first field that you usually encounter is Mechanics. Mechanics studies the so called mechanical motion - the relative displacement of physical bodies with respect to other bodies or parts of the same body with respect to other parts. The necessary mathematical techniques to grasp the concepts in Mechanics are Calculus and Vector analysis. Nevertheless, one can appreciate the basic concpets even without such level of sophistication and Algebra, supplemented by Trigonometry and preferably Analytic Geometry might be quite sufficient.
I think you should concentrate on this field at first. This constitutes the bulk of a first semester General Physics course.
The other part is usually elements of Thermodynamics. Thermodynamics is conceptually very hard for the novice, and you should keep returning to it as you learn more and more physics. Thermodynamics is so beautiful because its laws are so general and do not depend on the particular structure of the physical system under consider, that the conclusions drawn from it are general and far reaching, although they lack particular details. To find the details, one must turn to Statistical Physics, the study of systems composed of collosal number of units (atoms, molecules) through the use of the methods of Mathematical Statistics.