Answer:
Sin 18° = cos 72° and sin 72° = cos 18°
Step-by-step explanation:
According to trigonometry identity;
sin Ф = cos(90 - Ф)
for Sin 18° = cos 72
Ф = 18°
Substitute into the expression
sin Ф = cos(90 - Ф)
sin 18 = cos(90 - 18)
Sin 18 = cos 72
Hence the statement id true
For sin 72° = cos 18
Ф = 72°
Substitute into the expression
sin Ф = cos(90 - Ф)
sin 72 = cos(90 - 72)
Sin 72 = cos 18
Hence this statement too is correct
The two correct statements are Sin 18° = cos 72° and sin 72° = cos 18°
