Question

if triangle ABC is equals to 4 cm B is equals to 7 cm C is equals to 9 CM then tanA/2
equals to ​

Answer 1

Given :  triangle ABC is equals to 4 cm B is equals to 7 cm C is equals to 9 CM

To Find : tanA/2

Solution:

a = 4 cm

b = 7 cm

c = 9 cm

a² = b² + c² − 2bc cos(A)

=> 4² = 7² + 9² - 2(7)(9)CosA

=> 16 = 49 + 81 - 126CosA

=> 114 = -126CosA

=> CosA = -114/126

=> CosA = -57/63

CosA =  (1 - tan² (A/2))/(1 + tan² (A/2))

-57/63 =  (1 - tan² (A/2))/(1 + tan² (A/2))

=> -57 - 57tan² (A/2) = 63 - 63tan² (A/2)

=> 6tan² (A/2) = 120

=> tan² (A/2) =  20

=> tan (A/2) = 4.47

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Answer 2

Step-by-step explanation:

This is the Answer 1/√20