Any good way to get an intersection of 3planes?

I have three faces,but their face normals are very simlar to each other,and they are almostly paralleled to each other. a=[-0.996194973121394 -4.18489862633171e-06 -0.0871525989867842; -0.996194973121394 -4.18489862656107e-06 -0.0871525989867874; -0.990861867854174 0.00130908827787537 -0.134874182556999] Any good way to get an intersection of 3planes? Thank you!