Weds 29th Feb – sine, Cosine and Tangent ratios

LEARNING OBJECTIVE: TO understand the three ratios – Sine Cosine and Tangent

SUCCESS CRITERIA: You will be able to find the angle in a triangle given any two sides

STARTER: Work through Ex 12G on page 281using your calculator.

Discussion on any findings

LESSON: How to use sine and cosine on calculator to find length and/or height of triangles of any hypotenuse length and any angle

Lots of examples on IWB. Then have a go at the six questions on the IWB.

• Show how the SINE of an angle is constant for the ratio opp/hyp
  
• Show how the COSINE of an angle is constant for the ratio adj/hyp
  
• Show how the TANGENT of an angle is constant for the ratio opp/adj
  

Examples showing how to use the above ratios to find the angle(s) in triangles

Have a go at Ex 12 H on Pages 283 and 284 then Ex 12l on page 286, then ex 12J on Page 288

PLENARY: QUESTION / PROBLEM to solve.

If I know the hypotenuse of a triangle is 15cm and its height is 12cm. Can I work out the angle of the triangle and then the length of the triangle.