What is the formula of the angle of a V-groove?

1.	What is the formula of the angle of a V-groove?
A.	Sin A/2 = (d<sub>2</sub>-d<sub>1</sub>)/2 ‚Äö√†√∂‚Äö√†√´ (h<sub>2</sub>-h<sub>1</sub>)-((d<sub>2</sub>-d<sub>1</sub>)/2)
B.	Tan A/2 = (d<sub>2</sub>-d<sub>1</sub>)/2 ‚Äö√†√∂‚Äö√†√´ (h<sub>2</sub>-h<sub>1</sub>)-((d<sub>2</sub>-d<sub>1</sub>)/2)
C.	Cot A/2 = (d<sub>2</sub>-d<sub>1</sub>)/2 ‚Äö√†√∂‚Äö√†√´ (h<sub>2</sub>-h<sub>1</sub>)-((d<sub>2</sub>-d<sub>1</sub>)/2)
D.	Cos A/2 = (d<sub>2</sub>-d<sub>1</sub>)/2 ‚Äö√†√∂‚Äö√†√´ (h<sub>2</sub>-h<sub>1</sub>)-((d<sub>2</sub>-d<sub>1</sub>)/2)
Answer» B. Tan A/2 = (d<sub>2</sub>-d<sub>1</sub>)/2 ‚Äö√†√∂‚Äö√†√´ (h<sub>2</sub>-h<sub>1</sub>)-((d<sub>2</sub>-d<sub>1</sub>)/2)

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