Question

If cos is
2/
3
find the value of2sec ^2 + 2 tan ^2 - 9.

Answer 1

Let the angle be A.

cosA=2/3=adj/hyp.

2(sec²A+tan²A)-9.

secA=3/2.

²+opp²

3²=2²+opp²

9-4=opp²

√5=opp.

tanA=√5/3.

sec²A=(3/2)²=9/4.

tan²A=(√5/3)²=5/9.

2(sec²A+tan²A)-9.

=2(9/4+5/9)-9

=2(101/36)-9

=47/18-9

=-61/9.

Answer 2

Answer:

answer attached in photo