Answer:
sin²θ
Explanation:
To determine what we need to divide
by to yield
, compare equations:
![\textsf{Equation 1}: \quad \sin^2 \theta+\cos^2 \theta=1](https://img.qammunity.org/2023/formulas/mathematics/college/6z1gfm10mlqi4r2wtx8slgd5c8lp8e628k.png)
![\textsf{Equation 2}: \quad 1+\cot^2 \theta=\csc^2\theta](https://img.qammunity.org/2023/formulas/mathematics/college/pd13rkceyugyqfuvd2xqqd4e97zp1en4uu.png)
If we divide a term by itself, it will always yield 1.
Therefore, divide each term in the first equation by sin²θ:
![\implies (\sin^2 \theta)/(\sin^2 \theta)+(\cos^2 \theta)/(\sin^2 \theta)=(1)/(\sin^2 \theta)](https://img.qammunity.org/2023/formulas/mathematics/college/bu352kkjqiow7idqupalvegoiolqsgfp8i.png)
![\implies 1+(\cos^2 \theta)/(\sin^2 \theta)=(1)/(\sin^2 \theta)](https://img.qammunity.org/2023/formulas/mathematics/college/jancju7tk6uaghad6u5u73vyv9w9ft95ee.png)
![\boxed{\begin{minipage}{4 cm}\underline{Trigonometric Identities}\\\\$\cot \theta=(\cos \theta)/(\sin \theta)\\\\\csc \theta=(1)/(\sin \theta)$\\\end{minipage}}](https://img.qammunity.org/2023/formulas/mathematics/college/n97p606dugo2vc46qmkt06vm6tjbn0dowx.png)
Use the trigonometric identities for cot and cosec:
![\implies 1+(\cos^2 \theta)/(\sin^2 \theta)=(1)/(\sin^2 \theta)](https://img.qammunity.org/2023/formulas/mathematics/college/jancju7tk6uaghad6u5u73vyv9w9ft95ee.png)
![\implies 1+\left((\cos \theta)/(\sin \theta)\right)^2=\left((1)/(\sin \theta)\right)^2](https://img.qammunity.org/2023/formulas/mathematics/college/c3vmeq3bl2ufzuzfb2rlpp0fz1nvw854db.png)
![\implies 1+(\cot \theta)^2=(\csc \theta)^2](https://img.qammunity.org/2023/formulas/mathematics/college/y2p7i9ih3und3gh35h6khuycdonl3xlbl9.png)
![\implies 1+\cot^2 \theta=\csc^2 \theta](https://img.qammunity.org/2023/formulas/mathematics/college/pmpd7oz0tc26rq9t4d4cao3cph6gdlzd85.png)
Thus proving that sin²θ + cos²θ = 1 should be divided by sin²θ to yield
1 + cot²θ = csc²θ.