问题
填空题
若tanα=3,则2sin2α+3sinα•cosα+5cos2α的值是______.
答案
∵tanα=3,
∴2sin2α+3sinα•cosα+5cos2α
=2sin2α+3sinα•cosα+5cos2α sin2α+cos2α
=2tan2α+3tanα+5 tan2α+1
=2×32+3×3+5 32+1
=
.16 5
故答案为:16 5
若tanα=3,则2sin2α+3sinα•cosα+5cos2α的值是______.
∵tanα=3,
∴2sin2α+3sinα•cosα+5cos2α
=2sin2α+3sinα•cosα+5cos2α sin2α+cos2α
=2tan2α+3tanα+5 tan2α+1
=2×32+3×3+5 32+1
=
.16 5
故答案为:16 5