Question

Prove that:-

Sin ^2 72° - Sin ^2 60° => underoot5-1/8


✏✏✏want full solution

❌❌❌No Spam ans ❌❌❌

Answer 1

Answer:

Sin ^2 72° - Sin ^2 60° => underoot5-1/8

✏✏✏want full solution

❌❌❌No Spam ans ❌❌❌

Step-by-step explanation:

Follow me and mark me as brainliest

Answer 2

Step-by-step explanation:

A=18°

5A=90

3A=90–2A

cos3A=sin2A

① 4c³-3c=2sc

4c²-3=2s

4–4s²=2s+3

4s²+2s-1=0

② s=(-2±2√5)/8=(√5–1)/4

③ s²=(6–2√5)/16

④ c²=1-s²=(1/16)(10+2√5)=(5+√5/8)=cos²18°==sin²72°

⑤∴sin²72°-sin²60°

=(5+√5)/8–3/4

=(5+√5–6)/8

-------hence proved--------

=(√5–1)/8 ♬♬♬