Answer:
Step-by-step explanation:
Now we know that
sec²θ -tan² θ= 1 ,
So tan²θ =sec²θ - 1
So the left of the given equation will be
sec²20 + sec²40 +sec²80 - 3
So
1/cos²20+1/cos²49+1/cos²80 -3
Remember sec θ= 1/cosθ
So
= since secθ = 1/cosθ
we have
= 1.1324 + 1.7040 + 33.1634 - 3
= 35.9998 - 3
= 33
