I'm a sixth grader and don't worry if your a good student then it will be a breeze
Answer
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Step-by-step explanation:
Based on function transformations, the graph of y= cos(2θ), is the same as the graph of <span>y= cos(θ), with a component B of 2, in which case, it means the period is the only thing that differs
well the period for this function will then be </span>

so, the graph of is, the same as y= cos(θ), just shrunk by half horizontally
we can divide the composite shape into on quadrilateral and triangle as shown in the diagram. since the line that joins the two shape is parallel to the base AB, the angle DEC is 85°.The angle CEA is 180°- angle DEC = 180-85=95. Angle BCE is sum of angle CEA, ABC and EAB subtracted from360°= 360°-(95+95+85)=85°. Angle DCE is 120°- ECB=35°. So, angle CDE = 180°-(35°+85°)= 60°. For reference see the diagram.