Question

[Quynh Existn't]

Tính:
A = Sin 42 độ - cos 48 độ

B = cot 56 độ - tan 34 độ

C = sin 30 độ - cot 50 độ - cos 60 độ + tan 40 độ

Answer 1

[Nguyễn Việt Lâm]

\(A=sin42^0-cos48^0=cos\left(90^0-42^0\right)-cos48^0=cos48^0-cos48^0=0\)

\(B=cot56^0-tan34^0=tan\left(90^0-56^0\right)-tan34^0=tan34^0-tan34^0=0\)

\(C=sin30^0-cot50^0-cos60^0+tan40^0\)

\(=cos\left(90^0-30^0\right)-tan\left(90^0-50^0\right)-cos60^0+tan40^0\)

\(=cos60^0-tan40^0-cos60^0+tan40^0=0\)

Answer 2

[Nguyễn Lê Phước Thịnh]

\(A=\sin42^0-\cos48^0=\sin42^0-\sin42^0=0\)

\(B=\cot56^0-\tan34^0=\tan34^0-\tan34^0=0\)