Question

For triangle ABC prove that
Sec A+C/2= cosec b/2


Grade 9
trigonometry -complementery angles
pls urgent
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Answer 1

Step-by-step explanation:

 In an triangle, sum of angles = 180*

    A + B + C = 180*

    A + C = 180* - B  

   (A + C)/2 = (180* - B)/2

   (A + C)/2 = 90* - (B/2)

⇒ sec{(A+C)/2} = sec(90-B/2)

      In t-ratios, sec(90-θ)=cosecθ

⇒ sec{{A+C)/2} = cosec(B/2)

    Proved