Jika a + b + c = 180 maka sec (b + c) adalah?
Jawaban Terkonfirmasi
Sec (b + c) = sec (180 – a)
* Jika a sudut lancip maka:
sec (b + c) = sec (180 – a)
= – sec a
* Jika a sudut tumpul
sec (b + c) = sec (180 – a)
= sec a