# Maths Resource of the Week 20

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#### Core 2 – Trigonometric Graphs

• A dynamic way of exploring the three trig graphs.
• What is it? - I am constantly amazed what Excel can do, and this resource is right up there with the best. In my experience A Level students find it quite difficult to understand the fundamentals underpinning the three trigonometric ratios and to then link their definitions to the shapes and key features of their graphs. This approach should help make things a lot clearer. It links the three graphs to the unit circle and dynamically illustrates how each of the graphs are formed as you alter the angle. This should help students gain a better understanding of which graphs are positive/negative in which quadrants, which will feed through to their understanding of how to solve trigonometric equations. This is a great teaching aid.
• How could it be used? - The chances are that your A Level students will have met the shapes of the three trig graphs at GCSE, but may not be entirely clear where these strange graphs came from. Explaining that the Sine graph tracks the height of the right-angled triangle and the Cosine graph the base really helps students get to grips with the relationships between these functions. Increase the angle slowly, challenging students to predict what will happen (and why) at each of the key angles. Relating the Tangent graph to the gradient of the hypotenuse will also give them the best opportunity of understanding this funny looking graph. This resource can also be referred to when students first encounter trigonometric equations and the equivalence of solutions.
• How have you used this resource? - Please share your ideas below.