Simplify {{MATH_272}} {{CMD_273}} Start by saying {{MATH_274}} This means {{MATH_275}}. Apply cosine to both sides of the equation above, {{ENV_276}} Now we will use the Pythagorean Theorem to deduce {{MATH_277}}. If {{MATH_278}}, the triangle in question must be similar to this triangle: {{CMD_279}} {{ENV_280}} {{CMD_281}} From this triangle and our work above, we see that {{MATH_282}} {{CMD_283}} {{CMD_284}}