trigonometry law theory and mathematical formula equation, doodle handwriting icon in blackboard background with

analysis angle astronomy background blackboard calculation chalk chalkboard circle clever cos cosec cosecant cosine cotangent creativity design doodle education engineering equation euler formula fourier function fundamental geometric geometry graph handwriting icon illustration law learn learning mathematical maths mnemonics model pattern physics problem school science secant sign sine smart solution student study symbol tan tangent teacher text texture theory trigonometric trigonometry tutor university write